Delete QT3_US_SUPPORT from all CMakesLists.txt

SET( QT_USE_QT3SUPPORT TRUE ) is delete from all CmakeLists.txt and adapting the souces, but "FIND_PACKAGE( Qt4 4.6.3 REQUIRED QtCore QtGui Qt3Support QtSvg QtXml QtScript)" in the root-CMakeLists.txt is unchanged. So Q3*-Header like Q3PtrList will not produce an error.
Merge branch 'lesserQt3' of https://github.com/global667/qucs into lesserQt3

Conflicts:
qucs/CMakeLists.txt
qucs/qucs-filter/CMakeLists.txt
qucs/qucs-help/CMakeLists.txt
qucs/qucs-help/main.cpp
qucs/qucs-rescodes/CMakeLists.txt