Enable calling meneco from ASP data in addition to SBMLs

[cfrioux]

So far, an import of meneco in a python program requires SBMLs as input.
It would be useful to enable calling the program with draftnet, repairnet, seeds and targets already processed as ASP facts and atoms. That would help integration into other software.

[cfrioux]

Notable ongoing change: returning a dictionary of results rather than 7 lists/dicts because in some cases, the previous behaviour would have led to errors:

• no unproducible targets
• no reconstructable targets
  ...