Clarify and document required/supported libraries

at least until #490 is completed.

consumers can decide whether or not to include it in their app depending on the version of jquery they are using

Also, use a greater than instead of a tilde for defining the jquery requirement.
> Wait. We don't bundle this with our distribution? We absolutely should.

By "our distribution", do you mean the concatenated `jquery.wymeditor.js` and the minified `jquery.wymeditor.min.js`?

So, you mean that we should concatenate it at the start of that?

> (Assuming that jquery.browser gracefully degrades when used with older versions of jQuery). If it doesn't, then I guess this is the best strategy.

By "degrades", do you mean that when a `jQuery.browser` function is detected, it refrains from overriding it?

If you mean that, then we don't want that—we do want the new `jQuery.browser` from the plugin to override the old–version jQuery's `jQuery.browser` because:
 1. The plugin knows about IE11—it doesn't end up as Gecko.
 1. The plugin has `jQuery.browser.versionNumber`, which is a useful whole number, which we use in our code.