py3: implement __bool__ in addition to __nonzero__

py3: replace iter.next() by next(iter)

py3: replace xrange() by range()

py3: read sqlite3 data as bytes The py2 and py3 docs ([1] and [2]) disagree how to get bytes output, but it seems obvious that this should be "bytes" to be compatible with both. [1] https://docs.python.org/2/library/sqlite3.html#sqlite3.Connection.text_factory [2] https://docs.python.org/3/library/sqlite3.html#sqlite3.Connection.text_factory