FaceGen JSON configuration

# Faces of JSON
Modify the face generation system to be configured using JSON.
Adds a `facegen.json` file to the facegen folder containing the current face gen system.
Pre-loads the images used and keeps them within a FaceGenManager class, avoid reloading everytime a face is generated.

# Reason
Done this mostly as a learning exercise but also because of a [request on the forum](http://spacesimcentral.com/ssc/topic/1415-pioneer-question-time-ask-them-here/?p=37908) who wanted to add some robots and I promised... MONTHS ago that I'd look into it! Yikes that was a while ago.

Anyway this is part of that work.