lazyobjectlist: Make it work with gtk3

Change-Id: I900bf47cf8f38393fde3bbd8b245e1a504d12aaf
lazyobjectlist: add debug logging

I always add and remove this kind of logging when messing
with the model. Using a decorator will avoid any performance
implications when being turned off.

Change-Id: I10a5c15046722f284e5f4ecbccd64ce13b41dd36
Merge changes I10a5c150,I900bf47c

* changes:
  lazyobjectlist: add debug logging
  lazyobjectlist: Make it work with gtk3