Alphabetize class names in left-hand TOC of python API

[MicahGale]

Currently for some very populated pages of the python API geometry, tallies, are hard to navigate as they are not alphabetized.

I understand this order comes from trying to logically group them in the index, but without seeing that grouping it's hard to find what you want.

If it's possible to create a separate ordering/ TOC for the left hand TOC, I think this would make the pages a lot easier to navigate.