Mechanics: Implement Proper Slope Handling

[jeffreypersons]

~Implement advanced platforming mechanic~ Add proper slope handling

The game is making a pivot towards a sonic like platformer where the penguin can slide along a track-like course and collect items, among other things.

This means, as step towards having sonic like behavior is to having much improve handling for a variety of different surfaces, from sloped/curved/jagged, etc.

...In other words, more advanced collision detection is needed, whether it be through raycasting, composite colliders, or other techniques, as well as rotations of the colliders, balance checks, etc.

[jeffreypersons]

After merging in Integrate prototyped movement from test scene into penguin player #157 - I got this covered with slope handling.