some turret changes from the XT branch

git-svn-id: svn://svn.icculus.org/fs2open@11116 387891d4-d844-0410-90c0-e4c51a9137d3
this too

git-svn-id: svn://svn.icculus.org/fs2open@11117 387891d4-d844-0410-90c0-e4c51a9137d3
from xt branch: add some hysteresis to asteroid fields to prevent "popping" when an asteroid exceeds the bounds

git-svn-id: svn://svn.icculus.org/fs2open@11118 387891d4-d844-0410-90c0-e4c51a9137d3
from xt branch: remove unneeded parameters, tweak some assets, minor optimization

git-svn-id: svn://svn.icculus.org/fs2open@11119 387891d4-d844-0410-90c0-e4c51a9137d3
xt branch tweaks

git-svn-id: svn://svn.icculus.org/fs2open@11120 387891d4-d844-0410-90c0-e4c51a9137d3
xt branch: additional optimizations using RAND_MAX_1f

git-svn-id: svn://svn.icculus.org/fs2open@11121 387891d4-d844-0410-90c0-e4c51a9137d3
probably good to change the comment too

git-svn-id: svn://svn.icculus.org/fs2open@11122 387891d4-d844-0410-90c0-e4c51a9137d3
xt: sprintf length safety

git-svn-id: svn://svn.icculus.org/fs2open@11123 387891d4-d844-0410-90c0-e4c51a9137d3