Add metadata to hdf5 ouput

[RBCanelas]

It would be very useful if the hdf5 files were more descriptive.

A group with metadata such as -type of file (hydrodynamic, lagrangian, waterproperties, external interpolated solution, ...) -dimensionality of the encased solution (3D, 2D, 1D) -type of mesh -version of mohid or tool that produced it -...

Every file should have this printed by mohid, by default, to help with the development of more semantically intense post processing tools.