* Added Feature Flag support, run doodle with --experimental to enable
all flags. Eraser Tool is behind a feature flag now.
* + and - on the top row of keyboard keys will zoom the drawing in and
out in Edit Mode. The wallpaper zooms nicely enough, but level
chunkers need work.
* A View menu is added with Zoom in/out, reset zoom, and scroll to
origin options. The whole menu is behind the Zoom feature flag.
* Update README with lots of details for fun debug mode options to play
around with.
* pkg/keybinds holds central functions to check global keybinds, like
DebugOverlay (F3), Undo (Ctrl-Z), GotoPlay/GotoEdit (p/e), etc.
* The Tools menu in the editor mode lists out more options to select
various drawing tools (line, pencil, etc.) - and showing the hotkey
for each tool.
