Mathics3

-----

* 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

-----

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 behavoir.

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 fixe.

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

-----

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.

-----

* 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` wil
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`.

-----

* Packaging changes. Make sure egg/wheel/tarball has settings.m and GNU Readline inputrc files package
* Bump minimum Mathics-Scanner version. There was a small subtle bug in infix Function operators in that

-----

Administrative changes but necessary to get this working properly:

* Bump min version of mathicsscanner. There was a bug in mathicsscanner that prevented
the GNU Readline inputrc files from getting created properly.
* Include settings.m in distribution. There was a typo in setup.py for location of this file.