That means we can now have highlighters active at global, buffer, and
window scope. The add-highlighter and remove-highlighter syntax changed
to take the parent path (scope/group/...) as a mandatory argument,
superseeding the previous -group switch.
That way we get proper unicode support in regular expressions as long
as the current locale treats wchar_t as unicode codepoints.
Fixes#638Fixes#595Fixes#162