add USB temlpate for F303

F3:F303/USB_template/strfunc.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <stdint.h>
+#include <string.h>
+
+void hexdump(int (*sendfun)(const char *s), uint8_t *arr, uint16_t len);
+const char *u2str(uint32_t val);
+const char *i2str(int32_t i);
+const char *uhex2str(uint32_t val);
+const char *getnum(const char *txt, uint32_t *N);
+const char *omit_spaces(const char *buf);
+const char *getint(const char *txt, int32_t *I);
+//void mymemcpy(char *dest, const char *src, int len);