MentionMe 1.6 Release

Issues Addressed:

#4 updated MentionMe to work with MyAlerts 1.04's new settings system
#5 Implemented the versioning techniques I learned from pavemen and used in ASB
#6 Went through the mention_filter and shored up some holes in the logic
#8 solved as duplicate (because of wrong MyAlerts version)

Added the ability for admin to enable mention alerts for all users from the config-plugins ACP page.