Split live server tests into subcomponents within the test file
Sanity checking for servers that might send back the wrong (but equivalent) FETCH response data item

Gmail has an issue with the reverse - it will return BODY responses for
RFC822 requests, but that doesn't affect us.  But doesn't hurt to be as
thorough as possible.
[mms] Allow multiple live IMAP/POP3 tests to be run in a single PHPUnit instance.
[mms] Fix thread sort order when using the client-side ordered subject algorithm and there are messages with identical dates.

First bug fix due to the new live testing code. Yay.