Diff for Horde4/BCBreaking between 2 and 3

+ Backward Compatibility Breaking Horde Issues (aka Horde 4.0 TODO)



* Fix cloning behavior (See Bug 1410).

* Remove deprecated code in IMAP_Tree::.

* Move IMP_IMAPClient:: to Horde.

* Merge IMP_Thread:: to IMAP_Thread::.