- First controller implementation.

- Added AbstractChart class. Make other charts inherit it and implement a common interface.
- MainWindow now contains a TreeView, also communicates with Controller.
- On startup, a new Controller object is created and a method that starts the proper application logic is invoked.
App startup implementation.

- First Controller implementation.
- Added AbstractChart class. Make other charts inherit it and implement a common interface.
- MainWindow now contains a TreeView, also communicates with Controller.
- On startup, a new Controller object is created and a method that starts the proper application logic is invoked.