Improvement suggestion: Aligned Zoom

would be nice if you zoom with mousewheel, you would end up at "good scales" 100, 200, 300, 400 etc 
not sure how it's implemented but I suspect you could just change the multiplier from 1.1 to 1.0905077326652577

this is  2 ^ (1/8), but you could use any integer divider...

(additionally you might want to implement auto-snap to "good scales" if close)