Improve autodetection logic:
Improve autodetection logic:

- fix SIP API warning message if PyQt4/sip cannot be imported
- fix polluting pyqode.qt namespace: do not import *, just importing PySide/PyQt4/PyQt5 should be enough
- add more debug messages

pyQode/pyQode#17

pyQode/pyqode.qt,pyQode/pyqode.qt