TypeScript Type Declarations Improvements

[jonobr1]

Addresses issue 559 and resolves the following:

1. Adds extends to all inherited classes
2. Fixes all constructors to have better code hinting and optionality
3. Allows for the import via module or through the entire namespace. E.g:

import Two from 'two.js';
import { ZUI } from 'two.js/src/extras/jsm/zui';
import { Circle } from 'two.js/src/shapes/circle';

const two = new Two(); // Hints correctly
const zui = new ZUI(); // Hints correctly

const l1 = two.makeLine(); // Hints correctly
const l2 = new Two.Line(); // Hints correctly
const c = new Circle(); // Hints correctly

Unfortunately, Two.js requires both automated and manual amendments to the types.d.ts files in order to get to the state that it's currently at.