!! Give future long- and short-term developments

Short-term:
 1) implements and test new recurrence relations of effective core potential, and
    model core potential (Version 1)
 2) tests SPHMOM (needs to transform from Cartesian to spherical moments, we may first
    calculate several Cartesian moments integrals, and finally transforming them to
    spherical moments), gen1int.F90, GAUPOT, overlap distribution, GTO values using
    contracted GTOs
 3) implements and test the recurrence relations of diamagnetic spin-orbit coupling
 4) rewrites the DEBUG information in the codes, see the example in delta_hket.F90;
    implements test suite using finite difference
 5) implements and test new recurrence relations of inverse square distance potential
 6) finishes the Python interface
 7) tries to improve carmom_moment.F90, CPU time and memory
 8) improves the speed for QMM/MM, divide the potential origins as (a) those different
    from bra and ket centers, (b) bra center and (c) ket center
 9) tests hgto_to_sgto.F90
10) evaluation of Boys function (see FIXME in aux_boys_vec.F90), see FIXME
11) determines the symmetry of operators and derivatives (non-symmetric, symmetric
    or antisymmetric)

Long-term:
1) adds spin-orbit ECP (see for instance Int. J. Quantum Chem. 40, 773)
2) adds electron repulsion integrals?
3) for auxiliary functions F_n(T) and G_n(T), we can not compute "any" give n and T
4) other forms of operators, such as f(r)=1/r^m (m>=3), other versions of
   model core potential
5) periodic system?
