Add tarting optimization to DockOpt

[ianscottknight]

It seems that the practice of "tarting" can be a very effective way of improving the quality of docking configurations as evaluated by retrospective docking. Incorporating tarting as a new set of parameters may prove especially helpful in enabling DockOpt to find good docking configurations.

[ianscottknight]

https://wiki.docking.org/index.php/DOCK_3.7_tart

According to this, the process of tarting is:

1. Rename 3-letter residue code of target residue in rec.crg.pdb to be different from all canonical residue codes (e.g. MET --> MEU)
2. Add said residue code to prot.table.ambcrg.ambH with modified charge distribution across residue atoms
3. Replace representation of original residue in amb.crg.oxt with new one

[ianscottknight]

Note that this issue depends on #5 being completed first. #5 complete.

[ianscottknight]

@gregorpatof (Olivier Mailhot) has made strides in automating tarting optimization. Assigning him to this issue for collaboration.