Player crouch

[Noah2610]

While the player is holding down the crouch button (down), they should enter a crouched state.

This state includes the following changes:

• change hitbox
• change animations
  gets all new animations, with new Idle, Walk, etc. animations
• change movement stuff
  • MovementAcceleration
  • MaxMovementVelocity
  • BaseFriction

The crouched state should probably have its own entity config, but entering/exiting crouched state should be handled through actual code.

[Noah2610]

Crouching works with the abstract config "PlayerCrouch". Still needs a bunch of settings tweaks.

Closing for now.