implemented Checkbox control
reorganized TODO list into milestones
added class Model3dCache<T> and used it to cache model data
fixed memory leak in PolygonGraph; center, corner and edge objects held each other in memory
fixed rendering different stages of world generation
changed Vector3d and Matrix4d classes to be template specialisations of Vector3T and Matrix4T
updated to SQLite 3.8.7.1
updated Boost to 1.57
fixed compiling GameClient
updated SDL2 to version 2.0.3