Initial port qucs-lib to Qt4

Trying to remove any trace of Qt3Support.
Added Library Manager back to menu
Fixed the qucs-lib manager

It should now create the radio buttons for each user library on
~/.qucs/user_libs. It can rename and delete these files.

It compiles and runs *without* Qt3Support. Not tested thorougly thou.

Still TODO. Add an scrollable area just in case the user has
a long list of libs.
Merge pull request #17 from guitorri/qucslib_qt4

Ported qucs-lib to Qt4