Mathicsscript

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* 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

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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.

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* Allow command-line flag `-c` as an alias for `--execute` (along with `-e` to be compatible with wolframscript
* Better compliance on Windows which are GNU readline-starved
* Better unicode detection
* Accept newer mathics-scanner and Mathics3 versions

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* Fix `mathicsscript -f FILE` argument. See PR 26

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* All escape sequence for unicode and letter names added for GNU Readline
* Use Mathics Scanner package
* Support XDG-style configuration files

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* Fix ``Settings`$ShowFullForm`` now that we use Mathics supports Booleans better
* Show mathicsscript version on startup
* Add ``Settings`MathicsScriptVersion``
* Add all of the WL escape sequences
* Add conversions from WL Unicode to standard Unicode
* Shell escapes `!` and `!!` added

Incompatible changes:

* `-e` `--execute` is better suited for embedded use. It adds `--quiet` and shows just evaluation output as text