DataHandler: perform position data scaling.
ShakeShapeHandler: make scriptHeight an instance var.

Allows creation of drawings from the constructor.
Aegisub-Motion: Deduplicate tags after transform interpolation.
MotionHandler: destroy everything. And introduce blurScale.

The UI has been modified. The rounding options that have been around
from the beginning are now nonexistent. 2 decimal places should be
enough for pretty much anything.

I might change scale and/or rotation to 3 decimal places later.