Include the source files directly in the `.map` files [1] for two reasons:
1. In the simple theme, modules from `./node_modules` are only available on
developer's build host (a `make node.env` is needed to get the sources). By
example; in the `searxng.min.js.map` file, the `autocomplete.js` is linked at
URL:
../node_modules/autocomplete-js/dist/autocomplete.js
2. Later, when client sources has been moved out of the `./static` URL [2] to
the `<repo-roo>/src` folder, all JS sources are no longer available.
Drawback: `.map` files grow up in size, but this should not bother, because the
files are only loaded in debug mode.
[1] https://github.com/gruntjs/grunt-contrib-uglify#sourcemapincludesources
[2] https://github.com/searxng/searxng/issues/141
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>