* highlighter: Fix regions and patterns inside regions
* highlighting: Remove 2nd recursive highlightRegion() call
...and add limitGroup checks to pattern search.
* yaml: Add TODO type highlighting
* highlighting: Don't stop in highlightRegion() at empty lines
...because possible region line end pattern must be detected.
* syntax/sh: Correct string handling due to additional pattern handling
* syntax/sh: Remove slash in variables
* highlighter: Accept nested region only in case it's within the current reagion
* highlighter: Accept nested patterns only in case it's within the current reagion
* highlighter: Don't search for nesting in case the region end was found at start
Use the 'regexp2' library for lookahead and lookbehind in region
start and end regular expressions to support things like closing quotes
that aren't preceded by backslashes.
