[Evolution-hackers] Move IMAPX back to a module library for 3.12

[Matthew Barnes <mbarnes redhat com>]

The IMAPX classes were moved into Camel's public API to serve as base
classes for evolution-kolab.  But since Christian has parted ways with
us it would appear the evolution-kolab project is no longer active.

I'm planning a good deal of API changes to IMAPX over the next few
months as I work toward completing IMAP NOTIFY support, and I would
prefer these changes not be seen as breaking Camel's public API so I
have sufficient freedom to change what needs changed.

Therefore I plan to move the IMAPX classes back to a runtime-loadable
module library after the 3.10 release.  If the evolution-kolab project
is resurrected at some point in the future then we can renegotiate this.

Any objections?

Matt