Selecting a logarithmic result manually in the grid statistics data source
property editor now enables logarithmic binning and a logarithmic x-axis, the
same as creating the plot from a 3D view.
The previously selected result variable is tracked so that only an actual
property change enables logarithmic binning: other property edits leave a
user-selected binning mode alone, and binning modes stored in project files are
kept as-is on load.