#75 Vertical alignment of QwtPlots in custom vertical Layout and in Splitter

[Kerim Khemraev]

I wrote two classes that help to vertically align the QwtPlots.
There are three bugs that I cannot resolve but I think these classes are still usable (you always can drag Splitter or widget to update the layouts). The bugs are:
1. when MainWindow appears there might be misfits
2. when you fast resize MainWibdow then you get misfits in layouts
3. when you push "fullscreen" button on MainWibdow you also get misfits

I upload the test project that shows how to use it.
P.S. I'm beginner in C++ (half of a year experience)