fix Mantis #2933: don't output alt ship class information using fout_version

git-svn-id: svn://svn.icculus.org/fs2open@10116 387891d4-d844-0410-90c0-e4c51a9137d3
fix Mantis #2955: crash when trying to join multiplayer server, caused by trying to memcpy an integer into a ushort
(also add some sanity asserts)

git-svn-id: svn://svn.icculus.org/fs2open@10117 387891d4-d844-0410-90c0-e4c51a9137d3