Apply forces based on a location in space

Generate torque based on forces
Store rocket scale in rocket
Move rocket model around center of mass
Add v2cross to calculate the "cross product"
* Use it for torque calculations
Add camera code

* Move camera along with the rocket
Render background grid for context
Remove some commented out code
Add vec2 rotation (unsure if correct)
Change rocket graphics

Use a new rocket model
Add a particle system for main exhaust
Add customizable behavior to particle systems
* Define life, growth of particles, brightness, etc
Fire RCS based on defined points in local coordinate system

* Replaces ad-hoc math to generate those points, allows for
  more easily changing them in the future
* Use two seperate points for RCS instead of center point
Use rotation functions to transform the points to world space
* Add test code for rotation functions (should add more tests here)