Fix gcc warning in io/keycontrol.cpp

suggest parentheses around ‘+’ in operand of ‘&’ [-Wparentheses]
This code previously worked only by fluke!

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@10952 387891d4-d844-0410-90c0-e4c51a9137d3
From MageKing17: tweak team colors

While we're looking at the Team Color code, let's have a warning if
someone tries to name a team 'none', and avoid pushing duplicate teams
to the Team_Names vector.

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@10953 387891d4-d844-0410-90c0-e4c51a9137d3