remove a lot of repeated looksup into Game::ACTION

I'm not trying to be an optimizer, I'm just trying to shorten lines
pass in Actions to add_{counter,}action
Add option to toggle between NOTICE and PRIVMSG
save/load pm_users settings
add !notice to help
use nicknames in pm_users

storing the entire User object is hugely wasteful
test: Read the settings file of /dev/null

Oops, that was making all tests fail