import qwert1213131's code.
add STM32F30x_StdPeriph_Driver.
add Libraries/SConscript
enable STM32F30x_StdPeriph_Driver ASSERT.
update linker script.
update project and scons script.
add cpu and board drivers.
remove old file.
update usart driver for STM32F3xx.
update board.h
rename uartx to usartx.
clean up rtconfig.h
update project.
update board info.
add the lost file.