cleaned-up gpio external dependencies and supporting build script. made disis_gpio external into a comprehensive object for all things gpio, including pwm (both hardware and software) with sarcduino-like formatting and verbose output. The external requires sudo due to required access to /dev/mem and /sys/class/gpio

*added new externals for raspberry pi (disis_gpio for digital I/O and disis_spi for analog I/O using mcp3008 A/D converter). Provided preliminary help files. PWM on gpio needs to be tested further. So does the build script. TODO: add this to the installer, including 4755 chown_gpio script.

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)

removed clicks from multitap using variable delay (now has different temporary artifacts that actually sound pretty cool).

added one more k12 object and updated pd.tk to reflect new items in the k12 menu (including new minimum size)

added new abstractions to the K12 module (still need to integrate it into pd-l2ork and add help files)

slowed down the rate of update to avoid choking down the GUI (bumped update of the wii speed from 1 to 25ms)

numerous fixes and improvements to abstractions and help files including reworked image drawing logic, improved metronome preset ordering and updated presets throughout the demo and help files, improved icons, clean-up and optimization, beter enveloping, and more.