Note column actors and splines

This turns the note columns into full fledged Actors that theme code and fetch and manipulate.
It also adds support for notes to be controlled by splines (position, rotation, and zoom).
Splines have 3 modes:  Disabled (notes controlled entirely by ArrowEffects), Offset (notes controlled by ArrowEffects + Spline), Position (notes controlled entirely by Spline).
Still need to write documentation for all the new functions and settle how to handle tweening, but it's mostly ready.
Demo videos:  
https://www.youtube.com/watch?v=qfwZAh63B4Q  https://www.youtube.com/watch?v=rq5IGDinYUI
https://www.youtube.com/watch?v=aE2Dm1VekK8  https://www.youtube.com/watch?v=PZDzZAEXkR4


Side note:  Apparently the renovation that notefield rendering received during this actually sped up rendering.
My test settings:  Springtime with m25 speed mod and 1.5 distant in Consensual, with Jousway's Shadow3D noteskin.  Fast Note Rendering is set to true.
Mainline:  105-130 fps.  Most commonly around 120 fps, dropping to 105 fps in the thick stream and rising to 130 fps during the beginning.
Spline branch: (with rotation splines active)  120-130 fps.  Most commonly around 130 fps, dropping to 120 during the thick stream.
Anybody else comparing frame rates would be helpful, since speed of note rendering is important.