Limited support for cancels is back in place

[Philip Van Hoof <spam pvanhoof be>]

I've put back in place limited support for cancels. Now the refreshes
and the get_header operations are cancellable at the level of the socket
operations.

This limited cancel support does 90% of what 90% of the people want from
cancel support: cancelling a synchronisation of a folder in case you
decide to go to another folder (clicking around quickly).


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