BigBuf and tracing rework: allow much longer traces in in hf commands

- provided a BigBuf_malloc() function to dynamically allocate parts of BigBuf
  e.g. for DMA-Buffers, Frame-Buffers, Emulator-Memory
- the whole rest of BigBuf is now available for traces (instead of a small fixed amount)
- send actual traceLen together with trace data
- changed client side to cope with varying traceLen
- changed small buffers to automatic variables instead of parts of BigBuf

client/cmddata.h

@@ -60,4 +60,6 @@ int CmdIndalaDecode(const char *Cmd);
 extern uint8_t DemodBuffer[MAX_DEMOD_BUF_LEN];
 extern int DemodBufferLen;
 
+#define BIGBUF_SIZE 40000
+
 #endif