Merge wxQT branch into the trunk.

This merges in the latest sources from GSoC 2014 wxQt project with just a few
minor corrections, mostly undoing wrong changes to common files in that branch
(results of a previous bad merge?) and getting rid of whitespace-only changes.
Also remove debug logging from wxGrid.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77455 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775