Refactoring of cxcss and channel/frequency scanner code

app/chFrScanner.h

@@ -0,0 +1,18 @@
+#ifndef APP_CHFRSCANNER_H
+#define APP_CHFRSCANNER_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+// scan direction, if not equal SCAN_OFF indicates 
+// that we are in a process of scanning channels/frequencies
+extern int8_t            gScanStateDir;
+extern bool              gScanKeepResult;
+extern bool              gScanPauseMode;
+
+void CHFRSCANNER_Found(void);
+void CHFRSCANNER_Stop(void);
+void CHFRSCANNER_Start(const bool storeBackupSettings, const int8_t scan_direction);
+void CHFRSCANNER_ContinueScanning(void);
+
+#endif