Started refactoring the code

- Can now zoom without selecting the zom tool
- Moved updateCursor to the tool class, deleted _updateCursor.js
- Removed as many references to canvas as possible, removed every global reference to context
- Added methods in Tool class to move the brush preview

js/tools/_select.js

@@ -2,6 +2,7 @@
 
 new Tool('rectselect', {
 	cursor: 'crosshair',
+	brushPreview: true,
 });