[RFC] Add the ability to use template inheritance

[zomars]

By using a template rendering engine like Nunjucks you can have all the added benefits and it fits right into the WSK workflow like a Glove. For anyone that has used Twig or similar templating engines will know about what I'm talking about.

Two benefits of template engines:

1. It lets you break HTML code into smaller files
2. It lets you use data to populate your markup

I've already did a fork where I implement this in WSK and it works like a charm, I can make a PR with no problem. You can check more information about this topic here.