Cosmin: Added dynamic frames

Added the JFXTras library and used it to add a dynamic window for the
Dispersion calculation.
An usable interface to add more windows id defined in
EcoRiskController.java, the controller for the Dispersion is
DispersiaController.java.
The fxml code for the Dispersion calculation was moved in
Dispersia.fxml, that will be loaded for the new Window.

TO DO:
1. Disable the toggled "Dispersia" button if the window is closed using
it's own close button.
2. Close the wondow when the Dispersia button is not toggled.
3. Minimize button is not currently working
4. Arrange the fields inside the Dispersia window
5. Clean and comment the code
6. Try to make the adding of a window more generic and clearer to
understand and use.