include "QDialog" etc not found after upgrade from 5.4 to 5.6

[d_stranz]

I'm not really a Qt Creator / qmake user; I work mainly in Visual Studio. There, I can specify include and library paths using environment variables: $(QTDIR)/include, etc. I would be surprised if you can't do the same thing in a .pro file. This would let you move the same project to different computers and it would work the same if you have the same environment variable on each system pointing to the correct place.