Added write out of upf files with pp_pseudo schema:
    ld1 can now write with the pp_pseudo schema if the use_xsd logical
    variable is given in the inputp namelist  with value .true.

    writing routines have been somewhat reorganized, the write_upf_module
    provides now the interface for both writing routines, actual code is
    instead in two specific modules. The pseudo_config type and the
    nullify_pseudo config subroutine have been moved in pseudo_types.f90

    write_upf_v2.f90 modified to use FoX libraries instead of iotk

    cleanup and documentation added.