- Added functionality to dump a reading:

	#./rfidler.py /dev/RFIDler 'set tag askraw' 'potset h 150' 'set fc 745' 'set rate 33' dump 6000
	sending 'SET TAG ASKRAW'
	sending 'POTSET H 150'
	sending 'SET FC 745'
	sending 'SET RATE 33'
	Wrote dump to dump_20141121-075357.xml

- Added functionality to plot from a previously saved reading:

	#./rfidler.py /dev/RFIDler load dump_20141121-075357.xml

- Added some logic to print out bit periods, i.e. the number of samples before the next toggling (not the true bit period, just to help determine the true bit period)
Output from ANALOGUE 100, when instead of using the actual value from read_adc(), we've put 0xAAAAAA as the
ADC value instead. As can be seen, the sprintf to databuffer overwrites the first two bytes with the ascii
values "32\0"-> [0x33,0x32,0x00]. The analogue data goes through masking, this 303000 is left. The remaining
two bytes affect the analogue curcuit didital reader output and bit period data.

Before patch:

    <Description>Time Based Sample Arrays</Description>
    <Coil_Data>
      <Description>Analogue Circuit Raw Data (HEX)</Description>
      <Data>
        303000a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8
        a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8
        a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8
        a8a8a8a8
      </Data>
    </Coil_Data>
    <Reader_Output>
      <Description>Analogue Circuit Digital Reader Output (HIGH/LOW)</Description>
      <Data>
        0202000202020202020202020202020202020202020202020202020202020202
        0202020202020000000202020202020202020202020202020202020200000000
        0002020202020202020202020202020202020200000000000202020202020202
        02020202
      </Data>
    </Reader_Output>
    <Bit_Period>
      <Description>Modulation Scheme Bit Period (TICKS)</Description>
      <Data>
        0100000101010101010101010101010101010101010101010101010101010101
        0101010101010101010101010101010101010101010101010101010101010101
        0101010101010101010000000000000000000000000000000000000000000000
        00000000
      </Data>
    </Bit_Period>

After patch:

    <Description>Time Based Sample Arrays</Description>
    <Coil_Data>
      <Description>Analogue Circuit Raw Data (HEX)</Description>
      <Data>
        a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8
        a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8
        a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8
        a8a8a8a8
      </Data>
    </Coil_Data>
    <Reader_Output>
      <Description>Analogue Circuit Digital Reader Output (HIGH/LOW)</Description>
      <Data>
        0202020202020202020202020202020202020202020202020202020202020202
        0202020202000000000202020202020202020202020202020202020200000000
        0002020202020202020202020202020202020200000000000202020202020202
        02020202
      </Data>
    </Reader_Output>
    <Bit_Period>
      <Description>Modulation Scheme Bit Period (TICKS)</Description>
      <Data>
        0101010101010101010101010101010101010101010101010101010101010101
        0101010101010101010101010101010101010101010101010101010101010101
        0101010101010101010000000000000000000000000000000000000000000000
        00000000
      </Data>
Renamed dump->store, added filename prefix, added l33t drawing mode, started on autocorrelation graph
Oops, forgot to reset some test values
Got the autocorrelation to work.. I think..
Merge pull request #17 from holiman/master

Save reading, load reading, small bitcount calculator