Improvements to animation system

[bcthund]

These are items to be added to make the animation system more versatile or function better.

[bcthund]

• [x] Improvements
  • [x] Allow animations to loop forever
  • [x] Animations should be auto destructable (remove from vector when finished)

[bcthund]

Other imporovements:

• [ ] Add built-in animations bin file
• [ ] Add enumeration for standard built-in animations
• [ ] Add offset to animations (so 3D world can billboard at other than center)
• [ ] Test auto destruction
• [x] Make GUI animation instance static
• [ ] Add tooltip to GUI animation