Trunk sync r11090.

git-svn-id: svn://svn.icculus.org/fs2open/branches/zookeeper@11091 387891d4-d844-0410-90c0-e4c51a9137d3
Fix various issues with $Acceleration Time.

git-svn-id: svn://svn.icculus.org/fs2open/branches/zookeeper@11100 387891d4-d844-0410-90c0-e4c51a9137d3