IR RX simple app (#218)

* split falling and rising ir rx events
* fix irda
* simple irda rx function for app
* add extern timer
* fix timer num for f2

firmware/targets/f3/api-hal/api-hal-tim.c

@@ -0,0 +1,8 @@
+#include "cmsis_os.h"
+#include "api-hal-tim.h"
+
+void tim_irda_rx_init(void) {
+    HAL_NVIC_SetPriority(TIM2_IRQn, 5, 0);
+    HAL_TIM_IC_Start_IT(&htim2, TIM_CHANNEL_1);
+    HAL_TIM_IC_Start_IT(&htim2, TIM_CHANNEL_2);
+}