improve Cue editor

[Doralitze]

Für den Cue-Filter muss eine Konfigurationsoberfläche gebaut werden. Diesbezüglich gerne mit @Doralitze Rücksprache halten, da eine tiefe Integration mit der Hardware hier sehr Sinnvoll ist.

[Doralitze]

The QTimeLine Widget might be a valid starting point.

[Doralitze]

Remaining tasks:

• [ ] implement utility buttons (issue #53)
• [x] implement preview filter functionality (issue #51)
• [ ] Add icons for transformation selection as hint
• [ ] Add functionality to compute in between key frames to have key frames that only effect a sub set of channels
• [x] Improve scrolling behaviour by including horizontal functionality and labels inside timeline view
• [x] Fix default cue selection (location and behaviour)
• [ ] Add text box for human readable name (defaulting to cue id) directly to cue editor and get rid of the data redundancy
• [ ] Draw Arrow on Cues that automatically jump to the next one
• [ ] Draw approaching symbol on cues that are exit cues (cues that are run at the end of a (repeating) cue before they switch to the next one) of others.

[Doralitze]

As the really critical issues have been dealt with, I'll move this issue to a later deadline.