Added BulletShapeSphere

This is a new collision component for sphere type objects.
Hopefully fixed mouse look issues with SDL
Removed SDL2_Image.lib from win32 projects

Added SOIL instead.
Added a Quit() method to IOpSys

This is a static method that must be defined in each derived IOpSys to
be specific. It is static to allow it to be called anywhere regardless
of having a reference/pointer or instance to an IOpSys.
Added some hardcoded events to BulletPhysics

There is a custom hard-coded event between the view and the airlock to
trigger quit.

Also there is a gravity setter that changes gravity based on normal to
the center of the sphere.
Merged in milestone1 branch
Vim failed me