Rename module loading commands

These had the "cmd_" prefix which we generally only use for RFC commands. The
names have been changed to match the other core oper commands.
ratelimit: Use txircd's util functions
cmd_rehash: Prevent an exception on server rehash
SQUIT is an RFC command and should probably be moved to that directory
Fix an inconsistent file ending
Refactor variables that shadow built-in names

Python doesn't care in most cases, but still something that should probably be
avoided if possible
Remove unused imports
Run actions on invite
Require a minimum channel status to use the INVITE command

This check was missing. I'm not sure if this was intentional, but in my opinion
it should be there, since the INVITE command is rather pointless if any user in
the channel can invite other people.
Nuke TestServ
Rehash the cloaking configuration correctly
Merge pull request #99 from Heufneutje/fix-cloaking

Rehash the cloaking configuration correctly
Implement the GLOBOPS command
Implement the KNOCK module
Merge pull request #95 from Heufneutje/module-globops

Implement the GLOBOPS command
Merge pull request #96 from Heufneutje/module-knock

INVITE changes and KNOCK module
Merge pull request #97 from Heufneutje/fix-many-things

Various fixes
Report oper attempts and write failed attempts to the log
Add a snomask for OPER attempts
Merge pull request #98 from Heufneutje/feature-oper-logging

Log and report oper attempts