getDimensions performance and style tweaks

Caching the jquery object and .data() might get you 1% better performance. It's not much, but it's worth it. Here's a simple jsperf (that doesn't really apply here since we're passing in a dom element and not a selector but is a good illustration anyways): http://jsperf.com/jquery-re-selecting-vs-caching-selections 

All the other variables are camelCased, so the dimension_lalala variables kind of stuck out too.