turn on -Werror and fix resulting errors

src/lib/conversion/rotation.cpp

@@ -181,6 +181,11 @@ rotate_3f(enum Rotation rot, float &x, float &y, float &z)
         x = tmp;
         return;
     }
+    case ROTATION_ROLL_270_YAW_270: {
+    	// unimplemented
+    	ASSERT(0 == 1);
+        return;
+    }
     case ROTATION_PITCH_90: {
         tmp = z; z = -x; x = tmp;
         return;

src/lib/rc/st24.c

@@ -72,7 +72,7 @@ const char *decode_states[] = {"UNSYNCED",
 #define ST24_SCALE_OFFSET (int)(ST24_TARGET_MIN - (ST24_SCALE_FACTOR * ST24_RANGE_MIN + 0.5f))
 
 static enum ST24_DECODE_STATE _decode_state = ST24_DECODE_STATE_UNSYNCED;
-static unsigned _rxlen;
+static uint8_t _rxlen;
 
 static ReceiverFcPacket _rxpacket;