Instead of each control function having separate code to parse sequences,
use shared code which splits it into a structure and parses parameters.

This fixes all sorts of ANSI bugs with leading zeros, default values, etc.

Not all sequences have been updated yet, but I'll plug away at this slowly.

Now, instead of a couple sequences having broken parsing, and them all being
broken in different ways, all sequences can be broken in the same way all at
once.