Support for extracting archive, add licence headers

Hi Damian,

I had a look at the ITEM..exe download yesterday in a hex editor and came up with the attached script, I've tested it on two files.

You'll need the pefile library to execute it as it turns out there's a absolute reference in the DOS Header of the exe.  See script source for more details.

I also added my name to the licence and updated the python sourced to add a header in case anyone wished to use them elsewhere so that we can be credited.

Chris

PS:  There may be a bug in your download script - I'll provide details when I have them... currently I'm getting the wrong file.