made the constants consistently used instead of strings

[cg-cnu]

storyboarder/src/js/window/toolbar.js

Lines 10 to 17 in 0ae65ef

	// TODO why even have these constants if we don't use them consistently?
	const BRUSH_PENCIL = 'pencil'
	const BRUSH_LIGHT_PENCIL = 'light-pencil'
	const BRUSH_PEN = 'pen'
	const BRUSH_BRUSH = 'brush'
	const BRUSH_NOTE_PEN = 'note-pen'
	const BRUSH_ERASER = 'eraser'

Fixed the issue noted in the todo. Replaced all stray strings in the file with respective constant 😄

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