[dev] no more categories patch

[Chuck Hagenbuch]

Quoting ViliusŠumskas <vilius at lnk.lt>:

> Correct me if i'm wrong but we don't need categories in prefs.php.dist files
> anymore. If so, I made a patch.

You're not wrong; the only hitch is that the conversion scripts to migrate old
categories/colors to the new system won't work if those preferences aren't in
prefs.php to be loaded.

> Also minor fix for mimp search_sources.

Committed, thanks.

-chuck

-- 
"But she goes not abroad in search of monsters to destroy." - John 
Quincy Adams