Completed and added benchmarks thanks to refactored benchmark code.

- moved benchmark from specific HTML mode folder to the generic test folder and refactored the benchmark engine to be able to run benchmarks on any parsers
- added npm script to launch the benchmarks
- added a benchmark for AT-HTML

Added a Fake Parser for HTML:

- uses the EXACT same grammar as the normal parser
- completely mocks the classes used by rules' actions, that is Node and NodeInstancier: they do NOTHING
- used to check the performance impact of the model classes, not the grammar-generated parser

Added a copy of the fast parser for HTML reusing the line and column functions of PEG.js. It is used to check their performance impact.