Some more nasty bugs fixed in the lf t55xx manchester_decode method.

ADD: a little function to see if GraphBuffer is not used.

client/graph.h

@@ -15,9 +15,9 @@ void AppendGraph(int redraw, int clock, int bit);
 int ClearGraph(int redraw);
 int DetectClock(int peak);
 int GetClock(const char *str, int peak, int verbose);
+bool HasGraphData();
 
 #define MAX_GRAPH_TRACE_LEN (1024*128)
 extern int GraphBuffer[MAX_GRAPH_TRACE_LEN];
 extern int GraphTraceLen;
-
 #endif