AIMWARE Essentials автор w7rus

Adds extra features to AIMWARE.net forum, specifically:

Features:
- Change forums themes, there are currently 2 third-party themes.
- Set image and video background to the forum.
- Change shoutbox height for easier reading and block offensive user messages by their username.
- Mark all forums read with one simple click. Requires mybb_post_key defined in settings.
- Import and Export settings in clipboard to share them across devices or friends.