Updated changes for 2.1.0 release (#56)

Updated changes for 2.1.0 release (#56)

* Updated changes for 2.1.0 release

Still needs some content for help.

* Updating patch level to 2.1.0

* More updates for 2.1.0.

* Fixed a broken merge (SVSXCF).

* Added missing extern.

* Updated version.c.SH (cosmetic fix).

* More updates for 2.1.0.

* Updated MODULE_INTERFACE_VERSION.

* Fixes for masked opers as they're already masked anyway.

* Let's make sure m_quit() will only check real users.

Currently, QUIT from un-registered clients (before NICK & USER) can crash the server because we're checking sptr->user->channels and sptr->user doesn't exist.

-Kobi.