Add text for COM_JEM_EVENT_FULL_NOTICE (Fix #806)
CB Plugins: don't require JEM (Fix #804) + beautify a bit
CB Plugin MyAttendees: count events only once (Fix #798)
Manage menu items on (un)install

- Uninstall: unpublish all JEM frontend menu items
- Install: update component_id on all old JEM frontend menu items
So after reinstallation Admin only needs to publish the menu items.