Allows compiling of wxFred2 on *Nix machines. Includes niffiwan's autocools, fixes some referencing issues with button graphics, and includes graphics for the program and application icons.

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9829 387891d4-d844-0410-90c0-e4c51a9137d3