A Project class contains project-specific data like name, undo_redo, frames, layers, tags and brushes. These variables have been moved from Global. This is the first step towards multiple tab support, where each tab will be a different Project.
The Canvas is now single node, instead of having multiple canvases for each frame. This should also be a performance optimization, since there are less canvas nodes, so there are less _input() calls. It should also fix a rare Undo/Redo issue with motion drawing and making lines. Could be unstable, needs more testing.
As a side effect, the guides are now the same for all frames, so this should also close #246.
Replaces nested Global.animation_tags arrays. Also replaced array.duplicate(true) with looping through the array and creating a new class for each array element, because duplicate(true) does not create new classes, unfortunately, which was causing issues with undo/redo.
ColorAndToolOptions has now the same code for left and right tool options, with more similar refactoring coming soon to places like Canvas and DrawingAlgos
Instead of having 2 variables for left & right nodes, use an array instead. This will help with better looking code, automation and less repetitive code, as seen in ToolButtons.gd. Move related refactoring will follow.
The old way weren't causing any issues, but it would have caused with double-digit version numbers. Also fixed backwards compatibility issue with 0.6.2 and previous versions.
It used to save the linked cel array which contained the canvas nodes into the .pxo. This, however, does not make sense, because the canvas nodes are being recreated when a .pxo is loaded. Therefore, they are different nodes than they used to be.
Now, an array containing the frame numbers which have cels linked for each frame is being saved and loaded into the pxo.
Made a new "src" folder that will contain the source code files, like all the GDScript and scene files. Please read this for more details: https://www.gdquest.com/docs/guidelines/best-practices/godot-gdscript/
It made no sense to keep scenes separate from their scripts. More file organizing will follow soon.
