IMAP support in mairix

http://sourceforge.net/p/mairix/mailman/mairix-users/thread/5409CDCE.6000803%40TZoNE.ORG/#msg32800160

I have added an IMAP client to mairix so that it supports indexing and searching messages found on an IMAP server and placing search results in a folder on the same IMAP server. Both features are optional, so that you can also index remote messages and store the results locally, or index local folders and store the results on IMAP.

My changes are made up of about 8 patches.