IMAP Keywords support.

[dzan]

Hi,

This adds IMAP keywords support ( custom flags ). The Flag enum is a class now. Predefined flags ( all the current ones ) are still only instantiated once. The Flag class is created to resemble an Enum. Only custom flags could exist multiple times at runtime.

Main feature for K-9 is a more complete IMAP implementation. I'll also use these as an option in the local saved searches feature. It could then allow a synced labeling of messages by the user.

[justdave]

Is this http://code.google.com/p/k9mail/issues/detail?id=4101 ?

[cketti]

A user interface is needed to make this change useful.

If anyone wants to work on this, feel free to contact us using the K-9 mailing list (http://groups.google.com/group/k-9-mail) or on IRC (#k-9, Freenode).

[dzan]

@cketti apart from there being no ui support yet iirc you didn't like the way I implemented this, feel free to close if I'm right. If not, adding a ui won't take long and is something I'd be willing to do. I'm thinking of a setting to turn it on/off and a small color strip for each keyword in a messagelist item, a bit similar to how the gmail app displays labels.

I'm not 100% convinced of this implementation myself anymore :)

[cketti]

That's right, I don't like the implementation too much. But we could refactor that later. I'm more than a bit skeptical about "adding a ui won't take long", though :)

Anyway, I guess leaving this pull request open won't hurt.

[cketti]

See #558