Two changes to fix a PySide problem (gh-50):

* PySide raises a RuntimeError when disconnect is called when there
  was no existing connection.
* Don't pass the handler argument to disconnect(), otherwise the subsequent
  call to connect(handler) seg. faults.
Merge pull request #53 from WarrenWeckesser/fix-pyside-crash

Two changes to fix a PySide problem (gh-50):