Add support for UPX packed EXE files

[ci-macpaw]

Originally reported on Google Code with ID 305

d235j.1:

Many Windows executables use .UPX packing. There isn't much software that can extract
this weird format (the commercial PE Editor can), but the packer is open source. It
would be nice if this were implemented.

http://upx.sourceforge.net/ for the packer.

[ci-macpaw]

paracelsus:

(Just cleaning up my issue list a bit.)