Two alternatives are provided: remove_attr and pop_attr. While the
former free's the Attr's data, the latter allocates a new Attr, to store
and return the data. Both functionality is provided by a single
(internal) static method.

This method needs to be used in places where freeing the src-pointer is
not possible, as it may be not allocated. If freeing is needed, it is
now in the responsibility of the caller. As it turns out this approach
is not even more useful, it is also less work, as it can be determined
from the fact, that adjusting the tests to the new behavior means
actually removing lines, that were previously working around the quirks,
that the old approach introduced.

The prepend_child and append_child methods were previously not tested.
They are now added to testing.

Hand in still missing tests.

added tests for getter

Added the allocation part of the implementation of attributes. Also some
tests were improved.
The functions to add and remove attributes are not implemented, as well
as the generation of the html for the attributes. Thats why also test
can't really test the attributes as it is not possible to add
attributes.

The function get_alloc_size was renamed to get_child_alloc_size as the
attributes will need another function.

Various remove methods were added, which are all implemented by an
static method, analog to the last commit.

The single method (formerly SH_NodeFragment_append_child) to add a child
at the end of the child list was replaced, by a bunch of methods to
insert a child at the beginning (SH_NodeFragment_prepend_child), at the
end (SH_NodeFragment_append_child), at a specific position
(SH_NodeFragment_insert_child) and directly before
(SH_NodeFragment_insert_child_before) or after another child
(SH_NodeFragment_insert_child_after). All these methods are implemented
by a single internal one (insert_child), as there isn't really much
difference in inserting one or the other way.
But this internal method doesn't check whether this insertion request is
actually doable, to save overhead as not every insertion method requires
this check. This is done by the respective method. However if the check
is not done correctly the internal method will attempt to write at not
allocated space, which will hopefully result in a segfault.

The child list is implemented as an array. To reduce the overhead to
realloc calls, the array is allocated in chunks of childs. The
calculation how many has to be allocated is done by another static
method and determined by the macro CHILD_CHUNK. This is set to 5, which
is just a guess. It should be somewhere around the average number of
childs per html element, to reduce unused overhead.

Also some predicates (SH_NodeFragment_is_parent,
SH_NodeFragment_is_ancestor) were added to check whether a relationship
exists between to nodes, thus whether they are linked through one or
multiple levels. These functions could replace the old ones
(SH_NodeFragment_is_child, SH_NodeFragment_is_descendant) semantically.
Furthermore they are more efficient as this is now possible to check
over the parent pointer. The internal insert method also uses these
methods to check whether the child node is actually a parent of the
parent node, which would result in errors later one.

The old test is now obsolete but remained, as it is not bad to test
more.

Removed some unnecessary type casts.
Added some forgotten calls to free.

Every fragment has a parent now, this is useful for both traversing the
tree and checking for cycles when a node is added, which would cause
problems, like freeing things twice or similar nice bugs. Both wouldn't
be possible otherwise. These features are not implemented yet.

The library provides a way to directly access the tag in a read-only
way, which saves an call to strdup. This is useful if only reading is
necessary , but needs special care by developers, as it is neither
allowed to modify it nor to free it. Disregarding this will lead to a
segfault in the best, and to silent data corruption and security bugs in
the worst case.

Internal struct definitions shouldn't be exported by header files.

The validator was used to check that every created tag is validate.
However I now think that validation should take place at a later time,
so it is not mandatory.
Thus developing the validator is now discontinued.

Instead of the trivial structure SH_Error, SH_Status is used. The name
was chosen, because error/status is set independently whether an error
has occurred. Beside the error type, it also contains the associated
errno and an error message. The error message is also printed, when it
is set. Generating error messages with variadic arguments is now also
supported.
There are also macros to check for a set status.

The exception handling was removed for the *_free methods, because they
can't fail predictably during runtime.

Unfortunately the compiler reports, that inside the macro set_status
printf may be called with NULL [printf (NULL)], although, this is
explicitly debarred.

This renaming is neccessary, as the future Fragmment will be the base
class to all Fragment types.

When the wrap mode is used, after each tag a newline is started. Also the
html is indented, which can be configured by the parameters indent_base,
indent_base, indent_char. The parameter indent_base specifies the width
the first tag should be indented with, while indent_step specifies the
increment of the indent when switching to a child tag. The character,
that is used for indenting is taken from indent_char. (It could also be
a string longer than a single character).
This aguments can't be set by the user, but are hardcoded (by now).

Fragment can be copied, either recursive (copying also all childs) or
nonrecursive (ignoring the childs, thus the copy has always no childs).
Adding the same element twice in the tree (graph) isn't possible, as
this leads to problems e.g. double free or similars.

The methods
- SH_Fragment_get_child (by index)
- SH_Fragment_is_child (non recursive) and
- SH_Fragment_is_descendant (recursive)
were added.

A Fragment can contain childs. When building the html, the childs html
is generated where appropiate.

A Fragment can output it's html. If there is an error the method aborts
and returns NULL.

Check in tests whether error really was written, by setting it to
undefined before each call.

Tests are done using check, allowing to integrate the tests into the
Autotools.
Methods that are part of another unit, but are called in this unit
aren't tested as this would interfere with the idea of unittests. This
also applies for purely wrapper functions, where a call is passed to
another unit.

Error handling is done by passing an Error structure as inout parameter
to functions that can fail on runtime predictable. This parameter is
always the last one. Methods, where this is not the case, doesn't have an
error parameter.
When an Error is detected, also an ERROR is passed to the log. Because
this isn't implemented yet, it is replaced by a nop.
The macro EXIT becomes now useless. It was used earlier in case of an
error, to terminate the program in the first place. This behaviour is not
userfriendly, but it can't be decided on the library's side, whether
there is an option to inform the user, something must be cleaned up or
even that recovering is possible at all.
Often these recognized errors are a non-working malloc or an over-/underflow.

Error handling can be ignored by the caller by passing NULL to the Error
parameter. Whether an error had occured, is also always possible to be
determined, by examining the return value. If the error occours in a
function returning a pointer, NULL will be returned. If it returns an value,
a special error value of that type is returned, i.e. PAGE_ERR in
SH_Data_register_page. If the return type would be void, a boolean is returned,
which tells, whether the method has succeeded.
(False means, that an error has occured.)

The error may have occured in an intern method and is passed upwards (the stack).
Internally errors are handled by an enum, but this must be considered an
implementation detail and can be changed in later versions.
It is in the responsibility of the caller to recover gracefully. It has
to be assumed that the requested operation have neither worked, nor
actually took place. Those the operation can be retried (hopefully).

Pages are hold by Data, CMS passes trough the call(s).

data handels all intern data and serves as a cache between the CMS and
the (R)DBMS.

cms will be the base "object", that performs all neccessary actions.