Feature Request: change semantics/HTML file names

[dave-green-uk]

First of all, fantastic tool, really changing the way we approach our modular front-end work.

We're renaming Nuclides/Atoms/Molecules to something slightly different to suit our tastes, but I'd like to also change the HTML file names.

I can see in the theme that these can he changed in header.pug. Without any deep diving into the code I initially wondered if renaming the .pug files in the root of the theme would work, alas it didn't.

Then I had a look through the codebase and spotted that the templateFiles has a hard coded array of the semantic names for each type of component:

var templateFiles = ['atoms', 'molecules', 'index', 'nuclides', 'structures'];

It would be awesome if we could specify an alternative array of templateFiles in the config file for use?

Then, after some changes to the theme, the semantic naming convention used could be completely changed, regardless of the fact that this naming convention still exists under the hood.

I'm happy to provide a PR for this if need be. 😄