Adds Canvas Resizing with Handles + Cleanup

[Step7750]

• Allows you to resize the canvas by dragging handles around it
• Fixes centering of new canvas objects on the viewport
• Cleans up canvas and function bar code (@ClaytonVis you were looking for ES6 anonymous functions :) They don't create their own closure scope)
• The canvas will resize on adding an image if there are no elements on the canvas

Closes #102