Topo Editor depth/mask/basinmask buttons don't work as expected.

[AidanJanney]

When using the Topo Editor, the depth, mask, and basinmask buttons have some weird and unreliable behavior. The Topo Editor plots the original bathymetry depth accurately, and the selection of the mask and basinmask options correctly switches to those views.

• After swapping to the mask or basinmask view, selecting the depth button again does not work. It instead switches to a plot with a color bar that almost acts as another land/ocean mask (see image below). I can't find a way to return to the original depth view after selecting another view. The same thing happens when selecting a cell by double clicking, it switches the depth view to the following plot that acts like a land/ocean mask.

• After erasing a basin and changing the total depth scale, the plot would sometimes show cells with depth less than the minimum depth as having depth. This is only shown on the depth display, the mask and basin mask still correctly show the shallow regions as land. See the image below, and the region next to the southern coast of Panama after the Pacific basin has been removed. I think this happens because the erase basin does not target cells that are under the minimum depth, so they still have their original depth after erasing a basin. This is actually what the issues in my original PR were referencing: Added "Remove Selected Basin" button to the Topo Editor #3 (comment).

• Cannot edit the minimum depth using the input box without receiving an error.

I think Manish has already addressed most of these issues in his PR: #5 (comment).

[manishvenu]

Yup, everything except the last bullet point I think!