Switch to pyqt4

I still have to check that the code works with pyqode.core 2.0 (but this
will for later)
Cacth up with the new pyqode.core PEP8 style
Follow pyqode.core renaming
Remove property grid since QPropertyRegistry does
not exists anymore
Merge branch 'develop' into develop2

Conflicts:
	pyqode/widgets/__init__.py
Fix QInteractiveConsole
Cleanup
TabWidget: fix bug where QCodeEdit loose its type

nd become QPlainTextEdit. The issue is most probably an issue in PyQt4
but we can workaround it by keep our own list of widgets.

The bug does not seem to appear anymore (but it needs more testing before making
a new bug fix release).
Merge branch 'develop' into develop2

Conflicts:
	pyqode/widgets/tabs.py
Finish 1.2.2