Major rewrite of number/color-finding code to remove dependency on
CodeMirror tokenization, which was simply too idiosyncratic and language-
dependent to be reliably workable. Fixes a number of issues with values not
being scrubbable or losing prefixes/suffixes while scrubbing -
AND simplifes the code quite a bit.

Also:
- Fix bug that prevented scrubbing inside inline editors in Sprint 33+
- Remove code for supporting old Brackets versions
- Rename some vars to be more clear on numeric values vs. strings
- Fix (unlikely) bug where consecutive nudge attemps at same line/ch pos
but in two different files would get entangled
- Rename some vars to highlight similar code in nudge vs. drag handling
(hopefully will consolidate in the future)