Compute map fitting [WIP]

[jaimergp]

We are adding a new objective to compute map fitting. This should be used together with energies or pseudoenergies. This objective volumefit will only provide number of atoms outside the map. Maybe we should do that as a % of the total; to be studied.

Checklist

• [X] Find Chimera's functions to do that: FitMap.fitmap.points_outside_contour
• [ ] Test whether absolute or relative numbers should be used
• [x] Interpolate a map out of a PDB file if needed (common in SAXS studies)
• [x] Create tests
• [ ] Update docs

To make the most of it, new features will be added to gaudi.genes.torsion as well, to be compatible with proteins and larger structures.