Changes:

• [Feature] Add new menu options for the cels context menu (accessible from the timeline) - “Select Cel(s) Content” (for Aseprite versions older than v1.3-rc2 it will appear as a single option)
• [Feature] Add new content selection options for selecting an intersection, **complement **and difference of selected cels content (only for Aseprite v1.3-rc2 or newer)