Instead of having a frame_duration[] array in the Project class. This makes the code much more readable and understandable, using less lines of code and, by avoiding an extra array, we also avoid potential out-of-bound array crashes.
The functionality for the user has not changed, and by testing so far I didn't find any issues.
* Sync for my local files to my repository
* This is frame properties update, it works but I can't be stored while
saving or loading and that makes crashes just the beggining :)
* I forgot this files :P
* Frame Properties update.
* Updating frame properties
* Update Translations.pot
* Changes to CanvasPreview and CelButton change
