morebits: Add support for single-request deletion/append/prepend

Previously we always fetched the token from the server. This is needless.
We can really just use mw.user.tokens.get('editToken') unless we need to
follow redirects or get the protection expiry time.

This commit has reminded me of the poor state of Morebits.wiki.page. It was
cobbled together in a hurry in early 2011 after Twinkle's screen scraping
system (Wikipedia.wiki) was broken by a server configuration change. In the
long run we should switch to mw.Api, which is officially supported by the
MediaWiki core developers.
speedy: Update delete reasons; remove redundant if block