Hide the application without exiting it

[hongpt79]

If press ESC button(on BlackBerry) LogicMail only hide. But it alway sync mail from mail server. It's same some client chat and check mail on BlackBerry. And when choose Exit LogicMail, it's really terminate.

[octo]

Specific request appears to be for an easier way to hide LogicMail while it checks for mail in the background. This will be part of the normal use-case for 0.5, so I am changing the version for this ticket.

[octo]

This task first requires the implementation of more intelligent network connection handling. That is because there is currently nothing to recover from network connection failures. Once that is in place, this should be a simple thing to enable. Before then, you can always use the task-switching hot-keys.

[octo]

This item has become a more vague headline for a collection of small items that will become necessary. Therefore, I'd like to more clearly define the tasks that this item will cover.

• "Close" and "Exit" menu items, on the app's home screen, need to perform separate actions
• Default home screen back-button behavior should be configurable between "Close" and "Exit". For now, "Exit" will still be the default, but that will change once #79 is implemented
• Current application state needs to be available somewhere global, like the runtime store. Along with this, the sync functionality needs to be aware of whether the app is currently running.
• LogicMail needs the initial hooks to at least know whether it is in the foreground or background, though any related processing (i.e. memory cleanup) may be deferred to another task
• Notifications should be aware of whether LogicMail is currently running, and bring it to the foreground if appropriate

[octorian]

In [917]:

Added initial auto-start support, completely refactoring the startup code for clarity and using a dedicated container object for runtime store state information. Also made "close" on MailHomeScreen simply hide the app instead of exiting it. (refs #329, fixes #78)