Ability to bypass the SPI2_IRQHandler used by the highlevel SPI interface.

See 'USAGE: own SPI code' section in libsystem/inc/Spi.h
Add a useful GDB macro in tools/armv7m-macros.gdb.txt for figuring stuff out when hanging in some default irq handler or something like that
Add STM32F4-Discovery pinout execel sheet
Add a few peripheral datasheets
Merge branch 'master' of github.com:cccc/U23_2013_examples
I2C sample added
SPI: Fix syntax for function pointers
Add register read with repeated start to i2c example
Add angle of magnetometer to i2c example
Merge branch 'master' of https://github.com/cccc/U23_2013_examples
Add 7 segment datasheet
added real-time clock example
04_gpiointerrupt: Enable the SYSCFG clock
Add another Audio example
s/Gaming_//
Remove .swp file. Ooops
added ADC example
Merge branch 'master' of https://github.com/cccc/U23_2013_examples

Conflicts:
	examples/target.mak