Throw gpio.h to a black hole; create new generic interface for gpio drivers

Stub STM32F0 GPIO driver, comment out all calls to the old driver
for rewriting against the new one.
Implement basic functions of STM32F0 GPIO driver
Change GPIO_write interface, rewrite old GPIO calls to use the new interface
Code cleanup to comply with project coding conventions
even more cleanup: changing coding style a little bit
now we can panic! (add panic() and kassert())
add kmalloc + kfree ^_^
Merge Adam's GPIO driver

Conflicts:
	chaOS/devices/stm32f0/peripherals.h
	chaOS/main.c