Modifying class default objects

[liquidev]

Class default objects (CDOs) are defined with a declarative defaultproperties block, and cannot be modified in any way during runtime. Which means we should try and do it anyways :^)

To do this we'll probably need some way of (still declaratively) assigning values to properties. Right now I don't have a good enough understanding of UProperty to do this, but it should be possible with some elbow grease and hardcore reverse engineering.

Use case pointed out in Discord: enabling otherwise dead code; see CanDoStylishMoves in Hat_Player which is disabled by default.