Slice Explorer Version #2

[johnkit]

Key features/updates:

• Update the layout to (i) display time as a horizontal slider below the view and (ii) display the slice position as a vertical slider to the right of the sidebar/drawer.
• When the time coordinate is represented by numpy's datetime data type, display time as an isoformat string. If DatasetViewer doesn't already do that, update DatasetViewer too.
• Add API and fields to scale the display independently in xyz. Include an Auto button to scale the dimensions so that the longest dimensions is no more than 2.5x the second-longest dimension. For example, if the x range is 7 degrees, y range 10 degrees, and z range 5000 meter, set the ranges to 1, 1, 0.005 (0.005 = 10 * 2.5 / 5000). Maybe we should make the 2.5 a settable property (no display)?

For extra credit

• Add a spinbox (?) to the right of the time slider to set the time index manually. (Use case is to make it easy to advance one index at a time.)
• Add code to Auto scale the shortest dimension if < 2.5x the next shortest.
• Add tooltips on the scale values to show their inverse (e.g. 0.005 => 200). ?Or maybe instead have a toggle button to switch between scale and inverse scale?
• Add labels to each slider, at least the 2 end points.
• Add a numerical field to display the current slice position/value.
• And I would sure like to add a mode/option where the explorer computes the mean value for the selected position and colors the points based on their signed difference from the mean value.
• Also would sure like to add openstreemap or some kind of map/reference displayed as an optional "layer" to the 2D mode.