UI revamp

The interface just got a big upgrade: it is cleaner, more lightweight, and more understandable. The color code of the layers is blue, the color code of the animations is red: it is now easier to understand if you are editing the layer or the animation.

Other improvements and fixes

• All operations now have a From / To toggle
• The timeline now indicates what to do to add the first animation
• Reordered and improved the Text Effect inspector sections
• For text effects, you can now split texts in letters
• You can now resize a text effect segment in the timeline
• You can now select an operation segment by clicking anywhere on the timeline
• Operation segments now display handles on hover
• Removed the size in the Artboard preset selector
• Improved the separation of the timeline and the canvas