Provides the ability to move and copy messages between folders. Issue

3.

Each remote Store (IMAP, POP3, WebDAV) can provide indications to the
higher level classes as to whether copy and move are implemented.
Currently, copy and move are only provided by ImapStore.java.  When
the facilities are not available, the user interface suppresses the
menu options.

The available destination folders can be configured using folder
classes.

Copy results in null message bodies in the destination copy of the
message until the next sync.  This is a problem that occurred with
deletes previously, and is likely a fault with the copyMessages method
of LocalStore.java.

Utilizes a modified version of the ChooseFolder.java Activity that
debuachedsloth contributed in a patch attached to Issue 285 on 16 Feb
2008.