Fix input lag with some ATI cards on Linux

From electrojustin; adds cmdline option to force a gl_finish call
prior to swapping buffers.

git-svn-id: svn://svn.icculus.org/fs2open@10979 387891d4-d844-0410-90c0-e4c51a9137d3
Fix Mantis 3090: Valgrind: Conditional jump or move depends on uninitialised value(s) in webserverApiRequest()

git-svn-id: svn://svn.icculus.org/fs2open@10980 387891d4-d844-0410-90c0-e4c51a9137d3
Fix Coverity ID 1230635 Unchecked return value

Check return code from lua EvalString on mainhall doors

git-svn-id: svn://svn.icculus.org/fs2open@10981 387891d4-d844-0410-90c0-e4c51a9137d3
From Coverity ID 1230636 Improper use of negative value

false positive; but add comment explaining why

git-svn-id: svn://svn.icculus.org/fs2open@10982 387891d4-d844-0410-90c0-e4c51a9137d3
Fix mantis 3089 (From MageKing17)

Move 3D ship select model drawing earlier so that the help overlay is
drawn over the top, not underneath

git-svn-id: svn://svn.icculus.org/fs2open@10983 387891d4-d844-0410-90c0-e4c51a9137d3
Fix mantis 3088 (from Yarn)

Fix two German keys not displaying in controls config

git-svn-id: svn://svn.icculus.org/fs2open@10984 387891d4-d844-0410-90c0-e4c51a9137d3