fixed menu
QDialog->QMainWindow
qucs-attenuator: added "help", modified the validator...
added CMake configuration files for Qucs GUI components

These are not (yet) supposed to replace the autotools building.
They can build and install all the GUI apps.
The CMakeLists.txt on each tool subfolder can be used as
an existing project on Qt Creator.
fix illegal character encoding
[cmake] Fix typo