Add cursor location to the status bar

[jncraton]

Display the current location of the cursor in the status bar in the proper units.

[jncraton]

This functionality has been added.

[tshields]

This is not actually true. it mostly works, but the scaling is wrong in a lot of places. Dr. Kiers observations are below:

• phase portrait one seems to work very well, x vs t – doesn’t seem to be correct, 1st return map – vertical direction seems correct, but horizontal direction seems incorrect (horiz reading may be the raw ADC value instead of the calculated voltage), 2nd return map – same problem as 1st return map, 3d phase portrait – vertical direction seems correct; horizontal seems incorrect, Bifurcation plot – vertical direction seems correct; horizontal seems correct, but rounded too far when in kOhm setting (rounded to the nearest kOhm). The rounding is most problematic when zoomed in, FFT – horizontal direction seems to be messed up.