reduce dependencies on driver/rcinput.h

* add new header that only contains neutrino_msg_t and friends, often this
  is all that's needed instead of full rcinput.h
* directly include rcinput.h in some cpp files instead of relying on
  accidental inclusion in some header
* add class forward declarations to avoid dragging in rcinput indirectly
This could use more work to further reduce the impact; maybe separating
the CRCinput::key_* constants from the rcinput class would be good.

src/system/settings.cpp

@@ -26,6 +26,7 @@
 
 #include <zapit/settings.h>
 #include <zapit/scan.h>
+#include <driver/rcinput.h>
 #include <gui/personalize.h>
 
 //enum PERSONALIZE_SETTINGS to find in settings.h