Added initial module TODO

When I can check what else I need to add, I will update this.
Fixed missing argument in README
Added more items to module TODO
Added irc:translate()

It takes the name of a sender and the arguments for that sender, and
returns the raw message.

eg. irc:translate("PRIVMSG", "#potatoes", "I like potatoes.")
is equivalent to
irc.senders.PRIVMSG(irc, "#potatoes", "I like potatoes.")

Added mainly for easier chaining of senders, ie. senders calling other
senders.