this should fix Mantis #2888 (allow for head.ani files without letter suffixes)

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@11186 387891d4-d844-0410-90c0-e4c51a9137d3
a more future-proof way to keep track of explicitly paused audio

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@11187 387891d4-d844-0410-90c0-e4c51a9137d3