additional memory management improvements

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9917 387891d4-d844-0410-90c0-e4c51a9137d3
merp

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9918 387891d4-d844-0410-90c0-e4c51a9137d3