Tokens that begin with two underscores __* or an underscore and an uppercase letter _X* are reserved,
so we should avoid those for our own include guards. The standard I'm settling on for foo.h is FOO_H_.
This hook and format are used for NOTICEs where the destination isn't
a channel and isn't yourself - eg. global targets like $$*.org. This was
already the case for PRIVMSGs (using the MSG_GROUP hook and format).
Previously these were being routed like a normal NOTICE, and those don't
display the target, so it looked exactly like a private NOTICE to you.
This will also catch server notices sent before you're registered.
