feature request: enable sorting white/blacklist by type

[sporkman]

This is a minor nit, but I've had a few users complain about it since moving from squirrelmail to roundcube. Currently the list of whitelist/blacklist addresses is sorted by address. It seems people like to view these lists not so much by email address, but by the type of rule (whitelist/blacklist).

Any thoughts on altering the sort to either:

• sort first by type, then by address
• have a clickable column header that would flip between white/black lists

My apologies if the issue tracker is not the place for feature requests...

[johndoh]

done in git-master