valid timestamps are actually > 0

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9992 387891d4-d844-0410-90c0-e4c51a9137d3
Fixed subtle breakage I caused to surface shields in r9794.

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9993 387891d4-d844-0410-90c0-e4c51a9137d3
redo r9978 with BUF-1 instead of x[BUF+1]

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9994 387891d4-d844-0410-90c0-e4c51a9137d3
Merge branch 'trunk' into cmake
New try.