The tests from chompjs are copied.
The comment out tests do not pass.
The implementation of js_variable_to_python has been updated:
* in the main looop, try to make the four different cases more clear
* handle decimal number like "-.5", "5." or "- 5" (without double quote)
* the character ` is seen a string delimiter as intended in JS
* the identifiers follow JS specification ($, _, letters and numbers)
