fixing printout of ibrav in xml data file
The printout of ibrav in xml data file could be wrong if the initializing routine had to be called multiple times because of the missed iinitialization of optional pointers to NULL pointer.
to allow different arrangement of axes for the same bravais lattice the new label
alternative_axesis introduced as attribute of atomic_structure in the xml schema, such arrangements correspond to non conventional values for ibrav such as ibrav = -ibrav or ibrav=91.
more pointers to optional arguments are now initialized run time for the same reason