Many testcases in texvcjs are defined in a ~50mb json file named: en-wiki-formulae.json.
Make this basic testcases also work in PHP.

• This file is probably to big to upload in the repository, therefore create a shellscript which allows enabling the json file for local testing.
• Add documentation in Readme.
• Define the tests in a corresponding php test file (for convenience the shellscript could run the testfile when the json file is downloaded)

There are some test files available

1. https://github.com/physikerwelt/wikiMath17/releases/tag/v0.3
2. https://raw.githubusercontent.com/wikimedia/mediawiki-services-texvcjs/master/test/en-wiki-formulae.json