Sindbad~EG File Manager

This files describes API changes in /media/ plugins,
information provided here is intended especially for developers.

=== 3.8 ===
* The final deprecation of core_media_manager::setup() means that this function will no longer be called.
The setup is now done in ::instance() so there is no need to call this.

=== 3.6 ===
* The following functions have been finally deprecated and can not be used anymore:
  * core_media_player::is_enabled()
  * core_media_player::compare_by_rank()

=== 3.3 ===
* core_media_manager setup() is now deprecated as it is now called when initialising core_media_manager::instance().
* core_media_manager is now final. Do not extend core_media_manager, instead create a media plugin.