This PR removes the custom exception handling discussed in #115. It should not affect normal operation (with one exception, see below).

Additionally, it changes the behavior of ScienceLab.write_bulk_flash() by changing the indentation level if this block:

        # verification by readback
        tmp = [ord(a) for a in self.read_bulk_flash(location, len(data))]
        print('Verification done', tmp == data)
        if tmp != data: raise Exception('Verification by readback failed')

In the current version, this block will never be executed because it comes after a raise statement. This does not seem intentional, so I fixed it. I have not tested it, but since it does not write anything to the hardware it should be safe.

My IDE also autoremoved some trailing whitespace here and there throughout the code.