Order drop-down projects by their full name

Fixes bug 2925.
Consider as live languages only those that have projects

Fixes bug 2924.
Hide native drop-downs while select2 elements are drawn

Although this serves as a workaround to avoid temporal UI glitches, we
should not be blindly relying on $(document).ready().
https://encosia.com/dont-let-jquerys-document-ready-slow-you-down/

Fixes bug 2926.