Set slider max to match cube file size

[BraydenThompson]

Closes #191

Discussion

Set slider values to max of each cube file dimension. Note: Aspect ratio within the ipyvolume still forced into a cube, this would need more complicated controls maintain the correct aspect ratio and be able to control which section is shown.

Testing

• Run build.sh and make sure new dependencies install in .venv
• Open up the notebook (make sure using the .venv Python kernel)
• Execute the first cell, and Import a non-rhopol.cube cube file, making sure that the sliders can go to the max of each dimension (-1 for indexing). fukui_negative_defect.cube was used as an example, and has dimensions of 120, 135, 320.
• Ensure that the 3d slice planes can go all the way to the edge of the graph.
  

[matthew-oberg]

Works!