Return early from _attr when there is no change in the value of the attribute.
Return early from _attr when there is no change in the value of the attribute.

This prevents any unncessary events from being triggered.

craftyjs/Crafty,starwed/Crafty,craftyjs/Crafty,maciekwie/Crafty,mucaho/Crafty,maciekwie/Crafty,craftyjs/Crafty,starwed/Crafty,mucaho/Crafty,starwed/Crafty,mucaho/Crafty,maciekwie/Crafty