python-qt4, sip4 and dy_python2 conversion

[Scott Kitterman <debian@kitterman.com>]

Currently python-qt4 is uninstallable due to breaks put in for python-dbus 
when it switched.  There's a proposed change to switch python-qt4 in DPMT svn.  
Since switching sip4 to dh_python2 will break approximately the same packages 
as switching python-qt4, I'm going to switch it too (working on that change).

This may affect packages that use sip4:

qtiplot  
eric  
pyqwt3d  
veusz  
libserial  
qgis  
pyqwt5  
scidavis  
serna-free  
ball  
salome  
calibre  
python-qt3  
python-qt4  
qscintilla2  
avogadro  
pykde4 

I think that these are almost all already affected by python-qt4 being 
uninstallable.

Scott K