Improve the implementation for collapsing of whitespaces

[EvitanRelta]

Current implementation for collapsing whitespaces is found in the collapseWhitespace pre-process.

The previous implementation was actually a text-process,
but was later was very roughly adapted into a bootleg pre-process:

(from collapseWhitespace.ts)

If anyone has any idea how to overhaul it to make it cleaner or faster, pls send help :(