allow mod authors to add their own icon
allow mod authors to add their own icon

- allow mod authors to dynamically add elements to the menu
- this can include background image, DOM events, etc.

Signed-off-by: 6d2e3dde545cd7af2cef6a7a740bddf65bea4f7d@gmail.com
mkress/SMF2.1,georaldc/SMF2.1,mkress/SMF2.1,margarett/SMF2.1,margarett/SMF2.1,StealthWombat/SMF2.1-more-forkery,MustafaCan/SMF2.1,georaldc/SMF2.1,MustafaCan/SMF2.1,mkress/SMF2.1,StealthWombat/SMF2.1-more-forkery