$.autoSizeTextArea worked very well when the proxy element and

<textarea> matched up perfectly (in terms of margins/padding and fonts)

and padding wasn't used in the text area. However, if one of these

conditions weren't true, incorrect heights would end up being

calculated.
We now assume that a minimum height is the full height of the field,

which may include padding. Since we are setting using height(), which

expects a content height without padding, we need to subtract any

padding that may be there. This helps to provide the heights that the

caller would expect.
We also set some sane defaults for the proxy element, removing any

margins, padding, and borders that may be there, and ensuring the font

is the same as the textarea.
This also updates setMinHeight() to trigger an auto-size. It was strange

that it didn't before, and that it was up to the caller to explicitly

trigger an auto-size.

Tested with some of the work I'm doing for a hybrid textarea/CodeMirror widget.

I was able to get consistent minimum heights, which was failing before.