Performance improvement suggestion: avoid calling hexWithoutQuotes when debug is not enabled

[yewming-chen-sndk]

hexWithoutQuotes function is always evaluated even when debug is not enabled especially for common write and _writeRead functions:

• LabJackPython/src/LabJackPython.py

  Line 570 in a2f13eb

  self._debugprint("Response: " + hexWithoutQuotes(result))

• LabJackPython/src/LabJackPython.py

  Line 317 in a2f13eb

  self._debugprint("Sent: " + hexWithoutQuotes(wb))

In a program that uses many i2c read/writes, hexWithoutQuotes + hex function can take over 2% of the runtime as shown in the following cProfile results:

   Ordered by: internal time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
    15647  103.943    0.007  104.009    0.007 LabJackPython.py:374(_readFromExodriver)
    15647    5.683    0.000    5.770    0.000 LabJackPython.py:248(_writeToExodriver)
    56/51    3.911    0.070    3.911    0.077 {method 'acquire' of '_thread.lock' objects}
        9    1.826    0.203    1.826    0.203 {built-in method time.sleep}
    31287    1.534    0.000    2.471    0.000 LabJackPython.py:3182(hexWithoutQuotes)
  1182380    0.628    0.000    0.628    0.000 {built-in method builtins.hex}
    15640    0.367    0.000  114.058    0.007 LabJackPython.py:564(_writeRead)

Suggest adding a simple call guard to avoid hexWithoutQuotes getting evaluated when debug it not enable. For example:

        if self.debug:
            self._debugprint("Response: " + hexWithoutQuotes(result))