Support Single Types file

[marklundin]

Previously the parser would be initialized with a directory path from which to load types

new Parser().init('/path/to/types/dir/');

The dom types are in seperate files, which would result in ~80 network request to various files.

This PR extends the api so that a path to a single file can be used instead, which allows for a single file to be loaded that represents all the types neccessary

new Parser().init('/path/to/types/dir/lib.d.ts');