Add option to select a single image in the umap window

[lstein]

Currently when the user clicks on a point in the umap window, the plotly click handler will select all the images belonging to that point's cluster. Please add an option to navigate to the slide corresponding to the clicked point, similar to the behavior of the seek-slider.

This option should be controlled by a pair of vertically stacked radio buttons in the umap window located underneath the EPS spinner. The buttons should be labeled "Click selects cluster" and "Click selects image". The value of this option should be saved in persistent LocalStorage along with the checkmark values.