update:
 + OPTIMIZE_MINIMIZE. improved the stop criteria for the CG minimization. tests on the ED code
show results with the same level of error between input and output if: i) gradient is
evaluated analytically, ii) tolerance on CG is kept around 10^-5.
+ PARSE_INPUT. update the help message now contained in the +save_input_file routine and called
std GNU help syntax (--help, -h, info, help).
UPDATE:

-OPTIMIZE: added 2 other CG routines (minimize.f and CG+ f77), interfaced in  OPTIMIZE_MINIMIZE.

-ERROR: added a quite useless feature in check_convergence named extend=F which increase the
error threshold by 1 order of magnitude and try to reconverge the iterations.

-IOTOOLS: in store_data_V added the possibility of saving a X array together with the Y vector,
as already possible for the dim=2,3 arrays.