[dev] PATCH Mnemo Category Based color highlighting

[Chuck Hagenbuch]

Quoting mike@graftonhall.co.nz:

> This patch allows uses to select a color for their categories in Mnemo.
> This color is used as the background color for the memo in list view.
> 
> This also adds a colorpicker to horde that could be used for a color
> picker for any preference without modification.

All committed, thanks!

-chuck

--
Charles Hagenbuch, <chuck@horde.org>
"After a few minutes the most aromatic and nice smelling Italian coffee 
 will come out of the exhaustpipe." - Our stove-top espresso pot