Timer & SysTick Timer example for the STM32F4
Added *.s as valid extension for the FileScanner
Update README.md

Change the links to the API documentation.
Templates generated (Typos)
Typos
UART: clearing Overrun Interrupt for F1,2,4
STM32 F4: UsartHal::ResetInterruptFlags implemented.
Merge remote-tracking branch 'upstream/develop' into feature/experimental_structure

Conflicts:
	src/xpcc/architecture/platform/cortex_m3/stm32/adc/adc_1.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/timer/timer_1.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/timer/timer_8.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/uart_4.cpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/uart_buffered_4.cpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/uart_buffered_flow_4.cpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/uart_hal_4.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/uart_hal_5.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/usart_1.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/usart_2.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/usart_3.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/usart_6.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/usart_hal_1.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/usart_hal_2.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/usart_hal_3.hpp
	src/xpcc/architecture/platform/cortex_m3/stm32/uart/usart_hal_6.hpp