Added two new tables ClickableQDTable and ClickableWTable and made Ws and Qs clickable in historical discharge calculation. The new tables define listener interfaces (clicked lower or upper icon) to listen to user clicks. In addition to this, there is an enum ClickMode with NONE, SINGLE and RANGE options, which allows to specifiy, which icons are displayed in the tables. NONE means no icon for user clicks, SINGLE has 1 icon, RANGE 2 icons for lower and upper.

- Validation of the input values of an incoming feed() call