Replace regex parser by a more robust implementation

[julien-duponchelle]

As soon vscode release:
Provide an API for advanced/semantic source highlighting
microsoft/vscode#585

We can publish a more robust implementation.

[polvalente]

As discussed in #16, I think it may be time to move forward with this plan. At least, change things up a bit in the token matching functionality. There are some limitations imposed by the usage of \b tokens as word boundaries, and we also have some problems with multiple modes (such as ignore-blocks, single-line expressions and opening tokens being the same as closing tokens).

As such, I think maybe we could move to using an external library to do the parsing heavy-lifting. I'm not familiar with the JS tooling for this, but Jison seems like a good lead.