Configuration Menu System support for external OSD

A quick hack to support config menu on external OSD, consisiting of:

- CMS-OSD partial separation (CMS and OSD reside in a same file: osd.c)
- MSP message injection (take it as server-push in client-server model)

src/main/fc/fc_msp.c

@@ -102,6 +102,15 @@
 #include "config/config_master.h"
 #include "config/feature.h"
 
+#ifdef USE_DPRINTF
+#include "common/printf.h"
+#define DPRINTF_SERIAL_PORT SERIAL_PORT_USART3
+extern serialPort_t *debugSerialPort;
+#define dprintf(x) if (debugSerialPort) printf x
+#else
+#define dprintf(x)
+#endif
+
 #ifdef USE_HARDWARE_REVISION_DETECTION
 #include "hardware_revision.h"
 #endif
@@ -1945,3 +1954,17 @@ mspProcessCommandFnPtr mspFcInit(void)
     initActiveBoxIds();
     return mspFcProcessCommand;
 }
+
+void mspServerPush(mspPort_t *mspPort, int cmd, uint8_t *data, int len)
+{
+    currentPort = mspPort;
+    mspPort->cmdMSP = cmd;
+
+    headSerialReply(len);
+
+    while (len--) {
+        serialize8(*data++);
+    }
+
+    tailSerialReply();
+}