Refactor tipElement to use a custom object

[stevenbenner]

The abundance of $.data() calls is starting to smell like a missing abstraction. It might be better to create a custom object with the required properties and references. Such an object would need to have all of the current $.data() variables including a reference to the jQuery/DOM element for the element.

This may have several benefits:

• Make it easier to lint/detect coding errors when accessing properties.
• Give JIT compilers a chance to optimize a well-known and reused object.
• Provide a very minor decrease in the time it takes to lookup property values.
• Define a hard coded contract for tooltip elements.
• Eliminate most of the name-based DATA_* variables.
• Opportunity to move hook-once code blocks to methods instead of "HasFoo" checks.

I'm not sure if this would have a positive or negative net effect on the file size of the minified code. As long as it doesn't add a significant amount of weight to the file then the readability improvement alone should justify the change.

Investigate if this is a good idea, and, if so, implement it.