Add generic property animation

[ensisoft]

Add a generic property animation that can be used to animate any property that can be interpolated.

Useful for simple cases such as modifying some property without making a whole entity animation etc.

implement this in the engine, provide a Lua api to generate the animations and assign them to a target object (entity, entity node, entity node attachment, UI widget) and keep the state in the engine/game runtime. On each update apply the property animation state on the target object's property