Lots of changes:
* modified:   src/semicontrol/gui/time_series.py
    * changed the __name__ == "__main__" block to create simulated
      instruments for testing
    * TimeSeriesPlotDataItem
        * fixed a bug where the first append to a new xLogBuf or yLogBuf
          would be appended twice
        * fixed data not appending to xLogBuf and yLogBuf if setData was
          never called
        * fixed clear method
        * renamed some range variables to rect
        * made 1024 the default max_size, stored in MAX_SIZE
    * TimeSeriesWidget
        * refactored and cleaned up _initSelectionPanel, splitting
          several parts into separate methods
        * now connects curves to instrument read signals when curves are
          enabled, and disconnect them when the curves are disabled
* modified:   src/semicontrol/instruments/config.py
    * removed testing simulations, and moved them into time_series.py
* modified:   src/semicontrol/instruments/interfaces.py
    * changed all the getX's to readX's
    * added signals that are emitted on read
* modified:   src/semicontrol/instruments/drivers/simulations.py
    * implemented changes to the instrument interfaces
* modified:   src/semicontrol/utils/ring_buffer.py
    * changed default dtype to float64, which is needed to hold
      the values from time.time()