WIP: threading
moved to a new package bc sqlite schema is no longer compatible
name changed to Stitch
fixed Tracker 49240045: attempting to load "More Mail" just gets duplicates of mails already shown
https://www.pivotaltracker.com/story/show/49240045
ignore .DS_Store files
[MessageContainer threadDepth] implemented
Merge branch 'threading'

Conflicts:
	Classes/MailboxViewController.m