- remove all the QT3_SUPPORT and compile without it

- remove all the QT3_SUPPORT and compile without it
- unvirtualize the methods of KPlotAxis, as imho it is not meant to be subclassed
- unvirtualize some KPlotWidget methods that doesn't need to be overloaded on subclassing
- moved some methods from inline to the relative cpp
- delete the KPlotObjects when emptying the list

svn path=/trunk/KDE/kdeedu/libkdeedu/; revision=491821