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.
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.
