added datatypes & some stubbed functions.

need to figure out what i'm doing with SyncStatus data, etc
& to flesh out Mailbox, Mail, & write query to Maildir to extract data
from filenames.
did some cleaning up on the order of the datatypes

need to put in some instance declarations so can use Eq, Show etc on
datatypes.
can parse a maildir & store some info

also cleaned up license and readme and stuff so that it's actually
githubbable