The Validator saves the tags as an array. Now also another information
is added, which slots aren't used currently to spare expensive calls to
realloc. This led to a mere reimplementation of the functions. Tags
can't be deleted by now, but the adding function supports reusing empty
slots. Also the reading functions have to determine, whether a slot can
be read or is empty.
The tests were adjusted, but are buggy, so they should be rewritten in
the future.

Additionaly some annotations for splint were added.

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.

Changing sefht_validator_test so that no memory leaks occur.

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

When a tag is made known to the Validator, which it already knows, the
old id is returned and nothing is added.
As this has to be checked by iterating over all known tags, a new helper
function is written for both SH_Validator_check_tag and
SH_Validator_register_tag: SH_Validator_get_tag.

Because we want also to test this function, we have to include
validator.c in the test file and override the static keyword by an empty
macro. It isn't possible any more to check for correct overflowdetection
by setting the index to UINT_MAX, because it will be iterated over all
data, thus raising an SIGSEGV when doing so. This is solved by filling
garbage unil UINT_MAX is really reached. As there would be an timeout
and it would fill RAM with around 40 GB of garbage, UINT_MAX is
overriden prior to inclusion of validator.c .

Validator serves as an syntax checker, i. e. it can be requested whether
a tag is allowed.