Tentative Processing support for libpd

This revision is brand new and largely untested; proceed at your own risk. The
packaged binaries are currently for Mac and Linux only, and the Linux binaries
may be wonky for now.

The directory PureDataP5 contains the source code and dependencies, configured
for development on Mac OS. You won't need to look at this unless you want to
participate in the development of this library.

If you just want to use libpd with Processing, then you can unpack the file
pdp5.zip into the libraries folder of Processing. On my Mac, that folder is
Documents/Processing/libraries.