New files and additions to old files.

Bit modifications to registers is not done (timers, usart, gpio??).
Modifications to allow STM32F4 and discovery board be the target for compilation.
Further STM32F4discovery changes.
Makefile enhancements to build multiple system variants separately.
Clock initialization fix

First initialize the HSI clock and change the clock source to it. After this continue with the STM code.
Linker script changes for STM32F4
Add Makefile support to build .bin in addition to .hex
Changed HSE_VALUE to discovery boards 8Mhz
First version of Nucleo-compatible Arduino GPIO pin definitions.