Removes the dependency on Node "path" module

[pedrolamas]

Removes the dependency on Node "path" module with a function to retrieve the basepath.

New basepath function has been lifted from here:

https://github.com/microsoft/vscode-textmate/blob/09effd8b7429b71010e0fa34ea2e16e622692946/src/utils.ts#L46-L55

I also had to update TypeScript dependency to fix the broken build.

Fixes #11

[pedrolamas]

@zikaari apologies for the direct ping, but any option of getting this reviewed and if accepted, merged?

Or is this repo not under active maintenance anymore?