notify user of regexp issues
stricter matching for flags in filteReddit regexp regexp
filteReddit.options.regexpFilters option to allow regexping

(more like, to disable it Just In Case)
filteReddit.options.regexpFilters.description links to /r/enhancement/wiki/.../regexp
Merge pull request #1843 from andytuba/filtereddit-regex-2

Filtereddit regex 2