Simplify rise/fall time measurements

[mliberty1]

Version: 0.9.7
Platform: All

Description
Sometimes, you want to measure the rise or fall time of a signal. With the existing Joulescope UI, you have to place horizontal markers at the start level and end level. You then have to compute 10% and 90% and place horizontal markers there. Finally, you can place a vertical dual-marker pair at the 10% intercept and 90% intercept. This is a lot of work. It would be great if the UI could do this automatically.

Expected Behavior
Place vertical dual markers around the region of interest. When rise/fall time is enabled, the markers should also display the 10% threshold, 90% threshold, rise/fall time, and dI/dt.