tools/: moved constant wave test mode code to libatrf (for sharing)

- lib/Makefile (OBJS), include/cwtest.h (cw_test_begin, cw_test_end),
  lib/cwtest.c (enter_test_mode_230, enter_test_mode_231,
  cw_test_begin, cw_test_end): moved constant wave test mode setup
  over from atrf-txrx.c
- atrf-txrx/atrf-txrx.c (transmit_pattern): use functions from cwtest.o

tools/include/cwtest.h

@@ -0,0 +1,25 @@
+/*
+ * include/cwtest.h - AT86RF230/231 constant wave test mode
+ *
+ * Written 2011 by Werner Almesberger
+ * Copyright 2011 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#ifndef CWTEST_H
+#define	CWTEST_H
+
+#include <stdint.h>
+
+#include "atrf.h"
+
+
+void cw_test_begin(struct atrf_dsc *dsc, uint8_t cont_tx);
+void cw_test_end(struct atrf_dsc *dsc);
+
+#endif /* !CW_TEST_H */