Adds a system for interpolation.
Adds interpolation systems to most of the bullet system.
Updates the test screen to use some bullet angle interpolation.
Adjusts the visibility of some things in interpolation system.
Generalizes the BulletInterpolator to be able to be used with any abstract projectile (renames it as well).
Updates the test screen to use the new projectile interpolator names.
Merge pull request #7 from mohammedh123/feature/update-function-helpers

Feature/update function helpers