Say "No" to Squares: Support for sprite sheets and sheet tiles with unequal width and height

Forcing sprite sheets and the tiles inside them to be square creates a lot of unnecessary and heavy white space, so I added support for sprite sheets that are not square, and (inside the sheets) tiles that are not square.

The necessary functions are overloaded so you can keep using the plugin just like before with only one parameter (widthHeight), or provide width and height separately.