common: Add inverted scope match rules to ignores

common: Add inverted scope match rules to ignores

Add support for inverted scope matching subrules to ignore entries.
A match now only happens when the string does NOT match ANY inverted
rules and matches AT LEAST one normal rule, unless no normal rules
exist (implicit wildcard match).

Example:
> #quassel*; #foobar; !#quasseldroid

Matches "#foobar" and anything "#quassel...", except for
"#quasseldroid"

Example:
> !#quassel*; !#foobar

Matches anything except for "#foobar" or anything "#quassel..."