Moved the extensions into wiringPi from gpio and made it more general purpose
more so that RTB and anything else can dymanically add devices
into wiringPi.
Changes to GPIO to updates for the SPI and I2C module loads
Added gpio unload for SPI and I2C.

Added a new way to setup SPI - by passing the mode in.

Support for the new Pi2 thing too

Added in generic 'blink' programs in the examples in C, RTB and Shell.
Updated wiringPi with a little big-file on the millis() function and
added in a new micros() function too.
Updated the examples with standard LGPL headers.
Added a new isr-osc.c test program - just for ISR timing purposes.