[rss] Replaced the toggle command with enable/disable
[rss] Replaced the toggle command with enable/disable

Probably anyone using this command will specifically want to enable or
disable a feed or feeds, rather than blindly set them to whatever they
were not.

Also fixed the regex in del and toggle to allow feed names with dashes.
Uname-a/knife_scraper,Uname-a/knife_scraper,Uname-a/knife_scraper