Patch from Andreas Pakulat to start providing better Qt 4 support for KDevelop 3.4
This patch:

-provides a new tab on the C++ configuration for Qt options
-moves the include-style option to the new tab
-provides configuration options for qt version, qt directory and designer
integration on the new tab page
-removes the designer integration configuration from kdevelop's settings page
-uses the already existing qt root entry in the project dom to create paths for
designer and qmake
-makes the configured qt directory override the qt dir setting in trollprojectpart.cpp
but keeps an explicitly defined QTDIR environment variable
-changes the logic of qt version and include style so that the include style can be
chosen freely for qt4. only the qt3 style is available for qt3.

More to come, thanks for the patch!