Added a new window (MainWindow)

New window for the calculator GUI
Added new window for test
Added comment to express coolness
Added test comment
Design of the calculator

I have added a lot of hboxes and vboxes . Added buttons and a text
field to work as a display text.
Updated design of calculator

Added tables instead hboxes and vboxes
Merge branch 'master' into Update
Changed design again - added button events.

There is no functions on the buttons yet. Needs implementation