[MAJOR] js: Move to webpack, pug from r.js, jade

[ix5]

Introduction

As already discussed in #754, try to make Isso more maintainable by facilitating modern testing practices.

This PR is a bit massive, but trying to make pug or other updated deps play nice with RequireJs just for the sake of a clean history is not something I'm prepared to do.

So, here goes:

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js: Move to webpack, pug from r.js, jade

In the interest of maintainability and integration with other testing tools, get rid of RequireJS (sometimes also called r.js or requirejs)

This necessitates the following changes:

• Removing the almond (AMD) module loader (superseded by webpack internals)
• Removing requirejs-text for loading static resources (superseded by webpack asset/source loader)
• Removing jade templating engine (superseded by pug, which represents the original jade project that had to be renamed due to trademark issues)
  pug v2+ no longer accepts 'mystr-{#foo.bar}'-style variables inside attributes, so *.pug templates need to be changed accordingly (mystr' + foo.bar)
  Note: templates have been moved to templates/ directory and renamed from .jade to .pug.
• jade-runtime and accompanying shims (superseded by simply pug-runtime)
• Move .svg files inside own dir, simplify loading via webpack's asset/source
• Add webpack config
• Add build scripts to package.json
• Adjust Makefile to use webpack via npm run
• Emit JS source map files from webpack (eases debugging)
• .gitignore JS source map files

While RequireJS utilized the following syntax:

define(["app/foo"], function(foo) {
  var bar = doSomeStuff...
  return bar;
})

Jest and other testing libraries need the NodeJS standard CommonJS style:

const foo = require("app/foo");
var bar = doSomeStuff...
module.exports = { bar };

Note: ES6/ECMAScript2015-style import has not been used since it would need transpilation via e.g. babel to be understood by Jest.

The RequireJS-style wrapping of all code inside define({...}) caused everything to be indented by at least one level.
To keep the changes in this commit manageable, indentation will be removed in a later commit.

isso: js: treewide: De-indent one level

Since switching from RequireJS to CommonJS syntax, the define() wrapper is no longer needed and as such, the the code formerly inside parentheses can be de-indented by one level.

isso: js: i18: RequireJS to module.exports

(Just an extension of previous commit, to avoid touching too many files at once)

demo: Use dev version of embed.js

This makes it easier to debug when testing. The demo shouldn't be user-facing, but either way, the performance penalty should be outweighed by debugging benefits.

isso: js: Reduce deps for app/lib/

(Just a minor commit to make the following unit tests easier)

---

Verifying

You can verify this commit by checking out this PR:

git clone https://github.com/posativ/isso isso
cd isso/
git fetch origin pull/800/head:pull-800
git checkout pull-800

And then installing everything as documented in docs: Install from Source.

Then, either embed Isso into your site or use the demo at localhost:8080/demo

---

A note for people from the future: You can use git blame --ignore-rev=<sha> to "ignore" the de-indent commits. See A better git blame.

Note to myself: We can probably ditch the templates altogether and simply use plain html with javascript string interpolation. That way, we lose pug, pug-loader and pug-runtime, which would make the bundle significantly smaller.

[ix5]

Pinging @stefangehn, @blatinier, @Lucas-C and anyone else interested in moving this project forward.

[ix5]

I've created a package for easier testing:
isso-0.12.5-webpack.tar.gz

[Lucas-C]

This is great!
Awesome job on moving everything to ES6 modules & webpack O.O
Maybe this should be merged as part of #801 as we would have the added confidence of the new tests?

[ix5]

This is great! Awesome job on moving everything to ES6 modules & webpack

Thank you for reviewing! Those questions you asked were all obstacles I stumbled upon while porting and was kind of too lazy to document. Thanks for keeping me honest ;) I'll document as I have written in individual responses inline.

Maybe this should be merged as part of #801 as we would have the added confidence of the new tests?

While waiting for the test suite to be adequate might sound like a sensible strategy for keeping bugs out, it'll also mean keeping up a massive amount of rebase work and effectively blocking any contribs to the client (or doing a lot of merge conflict work).

So I'll be selfish and merge this webpack/pug change soon-ish, before tests are done. My "justification" for this is that once 0.12.6 is released, we can afford to be open for integrating more major changes.