Bullet and box2d physics

[brenocq]

Multiple fixes were made to make sure box2d and bullet work properly and provide a common and easy interface.

Change log:

• Step control (simulate slower, faster, or in real-time)
• Graphics FPS control
• Draw collision contacts and collision shapes
• Better UI to configure physics
• Supported colliders: BoxCollider, BoxCollider2D, SphereCollider, CircleCollider2D, CyllinderCollider
• Supported joints: PrismaticJoint, RevoluteJoint
• Better atta config and state check (utils/config.h)
• Faster build when dependencies are already downloaded (no update check)