LF demod/cmd code cleanup + new lf search

cleaned up and error proof code.  plus added new command    lf search
when online it will lf read - data samples 20000 - and test for EM410x,
HID, IO Prox, and indala cards.  when offline it will test current
graphbuffer.

client/cmdlf.h

@@ -23,5 +23,6 @@ int CmdLFSimBidir(const char *Cmd);
 int CmdLFSimManchester(const char *Cmd);
 int CmdLFSnoop(const char *Cmd);
 int CmdVchDemod(const char *Cmd);
+int CmdLFfind(const char *Cmd);
 
 #endif