Port to vanilla Javacript, without jQuery or other dependencies

[onli]

This takes the code from the develop branches and moves it to modern JS: Regular modules, no jQuery, no url require module. To create a shariff.complete.js (for the demopage) I used rollup.js, like this:

rollup src/js/main.js -o demo/shariff.complete.js

It's likely there are alternatives. The javscript files with the modern modules also work directly in the browser, if you embed the main.js.

The facebooklike functionality is kept, but wasn't testable for me. I did not understand the purpose of the facebooklike_dlg.js with a reference to .less file (?), so I could not re-add it when restoring the dialog functionality. You might have to fix some aspects there.

In general, the whole code was only tested in the browser, without compiling the CSS.

The CSS side of the project wasn't touched. This PR does not contain the changes to the package.json or other documentation files.

[richard67]

Thanks. Will check on weekend.

[onli]

Cat pressed the enter button, I edited in a description now.