experimental support for SPV files now available

[Ben Pfaff]

I've been working hard to add PSPP support for reading SPV files.  I've
pushed what I have to the spv-reader branch at git://benpfaff.org/pspp.

The code isn't really ready for prime time, but if you just want to see
what works, you can visit https://pspp.benpfaff.org/ to upload an .spv
file and it will instantly translate it to a PDF for viewing.  (Don't do
this with your confidential data!)

I know it's not perfect, although it does a mostly adequate job with the
3000+ files in my test corpus.  I'd love to have feedback.

Thanks,

Ben.