Import YEEP-144 library 1.2 sources

Source-only snapshot of the 1.2 release. Drivers/ (the vendored ST HAL and
CMSIS) is excluded at 173 MB; fetch it from STMicroelectronics/STM32CubeH5 to
build.

YEEP144lib/include/YEEP144_DebugUART.h

@@ -0,0 +1,17 @@
+#ifndef __YEEP144_DEBUGUART_H
+#define __YEEP144_DEBUGUART_H
+
+#include "stm32h5xx_hal.h"
+#include "stm32h5xx_hal_uart.h"
+
+// Structure for UART info
+extern UART_HandleTypeDef huart3;
+
+void YEEP144_DebugUART_Init(void);
+int YEEP144_DebugUART_printf(const char * format, ...);
+
+void YEEP144_DebugUART_EnableCharMatchIRQ(void);
+void YEEP144_DebugUART_DisableCharMatchIRQ(void);
+void YEEP144_DebugUART_SetCharMatch(char match);
+
+#endif