Mathicsscript

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* 3D Graphics is now handled if Asymptote is installed.
* ``Settings`$UseMatplotlib`` and ``Settings`$UseAsymptote`` were added. The can disable the use of matplotlib and Asymptote when those are available.

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Fix packaging issues and be more tolerant matplotlib errors.

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* Many 2D plots and graphs can now be viewed via a matplotlib shell! PR 40.
* In prompt-toolkit:
- Better word-boundary detection for `NamedCharacters`, `Symbols`
- Include grouping start symbols "(", "{", "[" in detection

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Word completion detection was improved slightly. Previously, a grouping opener like "[", "(", or "{" would prevent word completion.

ASCII to unicode conversion was disabled since it was flaky and turned `===` into
garbage upon seeing `==`. Issue 38

In prompt-readline by default, inserting a "[", "(", or "{" will automatically insert the corresponding closing "]", ")", and "}".
Use f3 to toggle this behavior.

The packaging of 3.0.0 omitted some Readline inputrc files, and a JSON operator table. Issue 37
A few other Python packaging problems were fixed.

We've separated prompt_readline functions into its own module separate from the common prompt readline functions

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The primary readline interface has been redone using the excellent [prompt-toolkit](https://pypi.org/project/prompt-toolkit/).
This is pure Python code so it should be available everywhere.
We still include GNU-Readline for those situations where prompt-toolkit doesn't work. Select the readline style now with the
`--choice` option which can be one of `GNU`, `Prompt`, or `None`.

Prompt toolkit allows us to color input as it is getting typed. It also has nicer completion facilities, and sports a bottom modeline status bar.

There is still a bit of cleanup work to do to support GNU readline inputrc files better, or to handle completion better, but this will come later.

Independent of prompt-toolkit, there better pygments colorization using [mathics-pygments](https://pypi.org/project/prompt-toolkit/). Expect that to improve over time too.

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* There are now system setting and user settings. User settings take precedence over system settings.
* String output is now shown in quotes to make it more distinguishable from symbol and unexpanded
expressssion output. This does not follow how `wolframscript` works. Option `strict-wl-output` will disable this.
* Syntax and Highlighting is now done via the Python
[mathics-pygments](https://pypi.org/project/mathics-pygments/)
package. I think you'll find colorization more complete and
useful. Expect more improvements as mathics-pygments improves.
* Flag `--initfile` is now `--run` to have better conformance with `wolframscript`. In the future we hope
to support support conformance with `wolfram` if the` mathicsscript` (or code underneath) is called
using the name `mathics3`.