Tensor-sensor

The library seems to work and is stable so this is the 1.0 release. Thanks to sbrugman, we now display tensor element type information using both color and text. The color indicates the type (int, float, complex, ...) and the transparency level indicates the precision; the more saturated the color, the higher the precision. Github doesn't seem to render notebooks with pictures very well anymore so take a look at the [colab version](https://colab.research.google.com/github/parrt/tensor-sensor/blob/master/testing/examples.ipynb).

See PR [Include dtype information](https://github.com/parrt/tensor-sensor/pull/35) by sbrugman and then my subsequent changes.

Small enhancements (thanks to sbrugman):

* [Allow non .svg files with `savefig` arg in `tsensor.explain()`](https://github.com/parrt/tensor-sensor/pull/27)
* [Use latex `\times` not `x` for >3D dimensions](https://github.com/parrt/tensor-sensor/pull/26)
* [fix: specific mono fallback font](https://github.com/parrt/tensor-sensor/pull/36)

Plus a bit of code cleanup.

This was released 5/26/21 actually. Cleaned up parse tree construction to properly [handle ignoring parenthesized subexpressions](https://github.com/parrt/tensor-sensor/milestone/7?closed=1)

The library seems stable enough that I have moved out of beta into full version 0.1. The major new feature is to support JAX, but you can look at all [bugs and PRs for 0.1](https://github.com/parrt/tensor-sensor/milestone/5?closed=1).