Implement ADMIN-DIE commands

Added a function for each of the following commands:

ADMIN
AWAY
CNOTICE
CPRIVMSG
CONNECT
DIE
Add documentation

The functions mirroring official commands from the RFC now include the official
documentation.
Add documentation

The documentation now covers unofficial commands that are often implemented by
servers. The documentation is taken directly from Wikipedia and kept almost
verbatim.

NOTE: the official documentation seems to favor a 70 column width, which I see
no reason to abandon. The actual doc strings (not including the two padding
spaces for indentation) should now all be at most 70 characters long per line.
Merge pull request #11 from emiln/feature/commands/admin-to-die

Implement ADMIN-DIE commands

This resolves issue #11.