Make Special:MovePage's "Reason" field an input, not a textarea

This reverts r45571 (207e3e64), with some whitespace changes.

The original reason for making it a <textarea> was to avoid confusion
with the <input> for new page name. This is invalid now that the page
name field has been split into a namespace dropdown and an actual page
title field.

Bug: 13627
Change-Id: I5ab2092c32682e7a8a1494bf58553971568fa6cf
Merge "Make Special:MovePage's "Reason" field an input, not a textarea"