Fix mantis 3026

Update Linux --help option to show all cmdline options
Added data/checks for expected args to cmdline options
Add extra const-ness per m!m review

git-svn-id: svn://svn.icculus.org/fs2open/trunk@10706 387891d4-d844-0410-90c0-e4c51a9137d3
add support for InnoExtract on FreeBSD

git-svn-id: svn://svn.icculus.org/fs2open/trunk@10707 387891d4-d844-0410-90c0-e4c51a9137d3
use SHA-1 hashes

git-svn-id: svn://svn.icculus.org/fs2open/trunk@10708 387891d4-d844-0410-90c0-e4c51a9137d3
patch some holes in OS support

git-svn-id: svn://svn.icculus.org/fs2open/trunk@10709 387891d4-d844-0410-90c0-e4c51a9137d3