rollback and use $.fadeTo inside RESUtils.fadeElementTo

also some refactoring for readability
4.5.4 migrate: remove undefined from filteReddit.options.keywords.fields['unlessKeyword']
refactor filteReddit.filtersMatchString's excludeString / searchString checks

excludeString is now part of skipCheck
"what kind of comparison (if any)?" is now one long if-elif-elif
sanitize notificationThreshold better to preserve 0 values

also allow >100% threshold to avoid any notification.. goofy, but why not.