In an effort of ensuring consistent code style in test files as with
the "production" source code, we should run eslint as part of the
`$ npm test` script as well.

Most of the related fixes was done by `eslint` using the `--fix` argument.

Only special configuration tweaks for tests compared to the other
source code, is to allow functions declaration without names. The
rationale for allowing that in tests, is that the important reason we
have them in the source code (proper stacktraces) aren't as important
in test files.

It was not being asserted anywhere else, and I was suspecting that
PR #552 was changing current (and correct) behaviour.

This closes a couple of potential exploit scenarios.
Backtick (`) for older IEs and equals (=) for unquoted attributes.

Refs 83b8e846a3
Closes https://github.com/janl/mustache.js/pull/388

- Cleaner separation of responsibilities in the code between
  scanning, parsing, compiling, and rendering functions.
- Much faster

This replaces the soft escaping ('&' -> '&') with strict escaping ('&' -> '&'). This new behavior matches that of Ruby and other Mustache implementations.

Other points:
- `dot_notation` currency is changed to use an ASCII character, since the JS interpreters did not appreciate unicode.
- Forward slash is added to escape list c/o OWASP recommendations.