For protein based fitness effects - give option to not build contact map if map already exists

[ebrintn]

• Check if folder exists - this already happens
• Check if contact map in folder
• Check if contact map makes sense
• If so ask user if they would prefer to use contact map in folder rather than rebuilding, can be useful for rerunning same simulation if fails, etc.

[ebrintn]

Closing for now as protein contact maps have been removed from current version