make engine_wash_info a struct again

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9819 387891d4-d844-0410-90c0-e4c51a9137d3
derp

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9820 387891d4-d844-0410-90c0-e4c51a9137d3
turn mc_info back into a plain data struct, part 1

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9821 387891d4-d844-0410-90c0-e4c51a9137d3
turn mc_info into a plain data struct, part 2

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9822 387891d4-d844-0410-90c0-e4c51a9137d3