[UPDATE] comment header
[REFACTOR] cursor classification
[REFACTOR] replace case var with _internal const
[REFACTOR] move directories
[UPDATE] README.md
[REFACTOR] wrap up points arr into canvasStack
[FIX] #paint-color won't change background-color
[UPDATE] add undo/redo functionality, major refactors and update version to v0.1.0
[UPDATE] README.md
[UPDATE] README.md & move buttons on top of canvas
[FIX] undo/redo order bugs
[REFACTOR] undo/redo
[REFACTOR] minor refactor & bug fixes