moved gms- and shp-interface to FileIO-namespace; added a bit of documentation
added GMSH helper-classes to seperate namespace
removed --readNonBlankLineFromInputStream-- since it is not called from anywhere
added legacy interfaces to Legacy namespace
renamed FileIO/MeshIO to FileIO/GmshIO and moved GmshInterface and TetGenInterface on level up
fixed missing namespace changes
Merge pull request #318 from rinkk/FileIOCleanUp

FileIO structure clean up.
Split GMSH and Legacy namespaces.
Remove two unused functions from FileIO.