Clean and harmonize module_list.py

[fbissey]

module_list.py is quite messy in its current state. There are several things that can be done:

1. remove the unused debian bits
2. we have SAGE_LOCAL and SAGE_INC variables but there use iis not uniform
3. we also have numpy_include_dirs, numpy_depends, flint_depends, singular_depends and ginac_depends and most of them are under-used.

In this ticket I remove old debian stuff, use SAGE_INC, SAGE_LOCAL and the other variables in a uniform fashion removing all instances of SAGE_ROOT +/local/... and so on to replace it by the appropriate variable.

[fbissey]

patch to module_list.py