#35 Python 3 compatibility

[Gustavo Velasco-Hernández]

I found that using 2to3 is not enough for Pyserial works properly using python3 [#161]. I've found that write method in serialposix.py use d = to_bytes(data). That works for pyhton2 but not for python 3. I made this modification and now my application works fine.

original:

# Previous code ...
def write(self, data):
        """Output the given string over the serial port."""
        if not self._isOpen: raise portNotOpenError

        d = to_bytes(data)

Modified:

# Previous code ...
def write(self, data):
        """Output the given string over the serial port."""
        if not self._isOpen: raise portNotOpenError

        if sys.version_info < (3,0):
            d = to_bytes(data)
        else:
            d = bytes(data,'ISO-8859-1')

[Chris Liechti]

pyserial expects bytes. any sort of encoding should be handler in the users code, not within the library.