added Environment for MPI initialization

This MR replaces the old AMDiS::init() - AMDiS::finalize() pattern with a RAII class Environment, to be instantiated at the begin of the main method, i.e.

int main(int argc, char** argv)
{
  Environment env(argc, argv);

  // get MPI rank and size from environment after instantiation:
  std::cout << Environment::mpiRank();
  std::cout << Environment::mpiSize(); 
}

the ``finalize'' is called automatically when env is destructed, i.e. at the end of main().

src/amdis/Environment.hpp

@@ -8,17 +8,17 @@
 
 namespace AMDiS
 {
-  /// Establishes an environemnt for sequential and parallel AMDiS programs
+  /// Establishes an environment for sequential and parallel AMDiS programs
   /**
    * This object initializes the MPI environement, parses initfiles and may
    * initialize other external libraries. It is constructed with the program
-   * commandline arguments. In its destruction, the MPI environemnt is finalized.
-   * In the vast majority of AMDiS programs, an instance of Environemnt should
-   * be desclared at the very beginning of the main function.
+   * commandline arguments. In its destruction, the MPI environment is finalized.
+   * In the vast majority of AMDiS programs, an instance of Environment should
+   * be declared at the very beginning of the main function.
    **/
   class Environment
   {
-    // insternal static container holding a pointer to the Dune::MPIHelper.
+    // internal static container holding a pointer to the Dune::MPIHelper.
     struct Mpi
     {
       static Mpi& instance()
@@ -52,7 +52,7 @@ namespace AMDiS
     /// Create an environment without mpi initialization, with a fixed initfile given as string
     Environment(std::string const& initFileName = "");
 
-    /// Create an environemtn with initialization of MPI and initifiles from commandline arguments
+    /// Create an environment with initialization of MPI and initifiles from commandline arguments
     /// or the provided initfile filename.
     Environment(int& argc, char**& argv, std::string const& initFileName = "");
 
@@ -62,7 +62,7 @@ namespace AMDiS
       return Mpi::instance().rank();
     }
 
-    /// Return the MPI_Size if the group created by Dune::MPIHelper.
+    /// Return the MPI_Size of the group created by Dune::MPIHelper.
     static int mpiSize()
     {
       return Mpi::instance().size();