initial commit of the custom raspberry_pi externals supporting read/write from digital pins, analog pins (using shield with a mcp3008 A/D converter), and netsend~/netreceive~ optimized for rpi (net objects being copies of work done in the core pd)
cosmetic fix
reapplied Albert Graef's patch due to wrong patch being applied for the delayed unbind. Still have to work on ensuring that there are no memory leaks in unique cases where an object unbinds a different bindlist when receiving a message to do so on another (faust being an example of this).