When a thread is 'destroyed' from the UI we delete its messages and mark
the thread as inactive, (in other words, keep it around as contact info).
Additionally, we only load active threads when initializing the UI, and
reactivate threads when new messages are added to them.
Conflicts:
js/models/messages.js
js/models/threads.js
js/views/conversations/show.js
Adds thread model/collection for managing conversation-level state, such
as unreadCounts, group membership, thread order, etc... plus various UI
improvements enabled by thread model, including an improved compose
flow, and thread-destroy button.
Adds Whisper.notify for presenting messages to the user in an orderly
fashion. Currently using a growl-style fade in/out effect.
Also some housekeeping:
Cut up views into separate files.
Partial fix for formatTimestamp.
Tweaked buttons and other styles.
