Fix user list parser so it recognizes @users as ops
main: Fix handling of edge cases in commands

Fix a bug where "/command" with no args would cause a crash
Add special case of "/ text" sending a message "/text"
Fix linter complaints

It still complains that "client is undefined" on 331/332, but that's it being wrong.
(client is a global that we expect has been created by then)
main: Clean up command handling a bit.
main: Add /msg and /memsg for private messages

/memsg is a /msg that is also a /me
herp: cleanup commands
main: Display Me messages that are also private.