* some minor hacking of the login progress to improve performance
* expanded the application exit sync dialog to be a general modal sync dialog that will display whenever appropriate (e.g. during initial setup, on manual "sync now" requests, and on application exit)
* added a progress meter and status messages to the modal sync dialog to provide users with a better understanding of what's going on, and to assist in debugging
* added ability to cancel a modal sync request, including on application exit. when cancel is clicked on by the user, it will attempt to cancel the sync at the next opportunity (i.e. before the next sync engine is processed)
A new preference called "waitOnQuit.enabled" was created. This preference controls whether Weave will perform any actions on quit. If false, Weave won't perform any actions on quit, nor wait for any running actions. If true, Weave will wait for any running sync to finish.
The old "syncOnQuit.enabled" preference now controls if Weave will actually perform a full sync on quit or not. If false, no sync is started, but we still wait for an active sync to finish, if waitOnQuit.enable is true.
Both options default to true.
