Added doxygen comments to Peer.h

Please review these and make sure they're correct. I haven't written the code, so I'm not 100% sure how all of it works.
Doxygen documented the Address class.

Also made a few minor fixes:
- Address IP/port are no longer unitialized when using the empty constructor(normally this is no problem, but stuff like this can come to haunt you)
- Address data is now protected, to ensure that no polycode user accidentally modifies the variables directly. Friend classing is used to give Socket access to internal data.
Doxygen commented the Server class.
Removed mentions of the word "game" in the documentation.
Merge pull request #184 from CIB/documentation

Added doxygen comments