Warning: not fully tested

+ removed some LEN=LEN_HREC for unrelated variables

+ removed unused variables

* modd_gridn.f90: all fields are now managed with TFIELDLIST
* added INI_FIELD_SCALARS subroutine
* corrected bugs for use of TFIELDLIST with all the PROGRAMS

Added fields: MY_NAME, DAD_NAME, DXRATIO, DYRATIO, XOR, YOR, WT

* added pointers to the data in TFIELDDATA type
 (via array of pointers (one per mesh))
* used the previous array of pointers for some fields
  -> modif of ini files for them
* added IO_WRITE_FIELDLIST subroutine to write
  a series of fields (i.e. provided for output)
* moved INI_FIELD_LIST from INITIO_ll to INIT_MNH
* added new fields to TFIELDLIST