some tests needed to be adjusted:
- ' ' * 256 (in python) now doesn't work as intended; they are considered
  space
- in auth tests, make sure txt RDATA containing a space is explicitly double
  quoted
- in Rdata_TXT_LIKE_Test::createFromText, removed the last test case because
  it's actually a valid representation as commented.  now the implementation
  correctly accepts it.