A merge folder type

[Philip Van Hoof <spam pvanhoof be>]

This implementation is being worked on: TnyMergeFolder in libtinymail.

The type will basically merge together a bunch of other TnyFolder
instances.

It can handle any TnyFolder implementation (it should even handle a
TnyMergeFolder as to-merge folder, but I haven't tried that yet, so let
me for now say: with the exception of the TnyMergeFolder implementation
itself. Although I haven't yet found a reason why it wouldn't work, it's
of course a little bit crazy to build a merge folder using other merge
folders).

This merge-folder feature will in future be used for search and
flattening folder-trees in case of E-mail clients that want to do the
REmail ideas.


Note that a merge-folder does not yet proxy the observer events
(although this will soon be fixed) and that the asynchronous methods are
at this moment simply called the synchronous ones. Error handling isn't
correct either, yet.

A merge folder wont make IMAP IDLE on multple IMAP folders magically
work. You do need multiple connections for that, which is something that
I'm not-so interested in for tinymail (mobiles don't always like
building a connection for each open folder over a network like GPRS).


-- 
Philip Van Hoof, software developer
home: me at pvanhoof dot be 
gnome: pvanhoof at gnome dot org 
http://www.pvanhoof.be/blog