clarify that some structs should now be treated as classes
change shockwave_create_info back to being a struct
fix some missing shockwave_create_info initialization

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9817 387891d4-d844-0410-90c0-e4c51a9137d3
queued_animation uses a mess of memcpy and memset, so make sure it's a plain struct!

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9818 387891d4-d844-0410-90c0-e4c51a9137d3