lf sim fixes/creations correct now

fixed lf simpsk
fixed lf em em410xsim
fixed lf sim  (can go right from lf search to lf sim if you have a
strong antenna - if not use a demod first)

client/cmdlfem4x.c

@@ -266,7 +266,7 @@ int CmdEM410xSim(const char *Cmd)
     /* stop bit */
   AppendGraph(1, clock, 0);
  
-  CmdLFSim("240"); //240 start_gap.
+  CmdLFSim("0"); //240 start_gap.
   return 0;
 }