2 new callbacks (PlayFastForward, PlaySpeed), modified Seek callback to take target time in seconds (instead of ratio of duration). Integrating this in Input Mapping GUI and Session saving.
Session stores list of all callback instances and reacts on input release by calling the reverse callback if it exists, or by finishing the ongoing callback. This means the behavior of Callbacks is different for those who are reversible (i.e. returns a non-null reverse) from those which do not have reverse. The reversible callbacks enforce to be exclusive while active (key pressed), others can be repeated and complementary (run in parallel).
Session contains a set of 'Batch' that are created in the Player (renamed from PlayGroups). Session InputCallback can now target either a Source or a Batch, using std::variant (new type Target). Input Mapping reacts to input to create callbacks to a target, either a single source (as before) or to a Batch (multiple sources).
The concept of 'Selection' evolves to accept sources of any type, not only sources that are 'playable'. This way user can create pools to reference in OSC and in Input Mapping.
WTF did I think it would be a good idea to delete a source in a separate thread? This obviously causes a crash. To be investigated when a source tailes to delete... but should not happen...
All Stream report failure with logs, read in InfoVisitor for Sources. ImGuiVisitor for Sources also detect failure of source and its stream.
Cleanup of unused includes and functions.
When a source in a session fails, it is not anymore deleted after update; the Mixer keeps it in the session but detaches it from the scene. This way the user can access the failed source in the navigator (listed in RED), and Replace the source. The Replacement of source is available for any source. The source visitor does not skip a visit if the source failed.
Changing icons of Player selection to 'CIRCLE' icons because the icon of Player is the CIRCLE with triangle. Also allows to have an icon for User Selection.
Add play/pause button on source icon in selection (dynamic or stored selection). Display source icon in lower left corner, instead of play status. Fix alignment disabled timeline. Minor bugfix.
Replace the 'inspector' menu in favor of a magnifying glass button at top right corner of imgui window for Player and Output preview. Disable the magnifying glass upon window unfocus.
Options to fit output window on all screens. Added doubleclic function to View class (Transition view and Displays view have specific reaction to double clic.
