Added a little extra info to two bmpman errors.

git-svn-id: svn://svn.icculus.org/fs2open/trunk@11160 387891d4-d844-0410-90c0-e4c51a9137d3
Clarified how to set a new variable with mn.SEXPVariables.

git-svn-id: svn://svn.icculus.org/fs2open/trunk@11161 387891d4-d844-0410-90c0-e4c51a9137d3
Fixed a FRED crash when using $Flight controls follow eyepoint orientation (patch by MageKing17).

git-svn-id: svn://svn.icculus.org/fs2open/trunk@11163 387891d4-d844-0410-90c0-e4c51a9137d3
gr_opengl_string retooled to use glDrawArrays. Should be a bit faster now.

git-svn-id: svn://svn.icculus.org/fs2open/trunk@11165 387891d4-d844-0410-90c0-e4c51a9137d3