Add a page for the Node.js-like module loader

[svaarala]

Node.js module loader is packaged as an extra (svaarala/duktape#796), add a proper, verbose howto for it. Rename the existing module howto page so that it's clear it's referring to the Duktape 1.x built-in module framework (which is also available for Duktape 2.x).

Some topics to cover:

• Getting started minimal example
• Properties of the module object, and comments on any differences to the Node equivalent; maybe showing an expanded example module object would be useful for illustration
• Implementing a basic Node-like resolve mechanism
• Implementing a basic load mechanism
• Resolve and load in both C and Ecmascript
• Integrating transpiling into module loading, this seems to interest a lot of people, and e.g. the Babel performance issues are worth noting (perhaps a module loader could, for example, perform hash- or timestamp-based caching)
• Loading DLLs
• Loading statically linked native code

Whenever it's obvious, it could just link to the Node.js API of course.

Page link proposal: http://wiki.duktape.org/HowtoNodejsModules.html.