Support zooming in Flot plots

[dpausp]

The navigation plugin is not working due to problems with JQuery 1.7.

Implement zooming with a "zoom stack":

• select a rect area to zoom in
• go back to last zoom level with button or right mouse click
• reset button to restore original view

Additionally, display a smaller overview plot like here:

http://people.iola.dk/olau/flot/examples/zooming.html

[dpausp]

navigation plugin in current devel version of flot works with JQuery 1.9.

Works, but zoom stack seems to be the better idea