[Feature request] Show spinning gif when loading results from the archive.

[gsiotas]

When loading tracks from the archive that takes more than 2-3'' to load, I think it is a good practice to show a loading spinning gif somewhere or in a modal dialog to inform the user that there is a process running in the background and the browser hasn't stop.

Thank you for the consideration.

[vitalidze]

I thought about it for many times. The tricky thing here is to not show the spinner until it is really loading for a too much time to not annoy the user (I don't like blinking). Probably it can be worked out some how with timers.

[vitalidze]

Implemented, written news, updated latest and demo versions.

[gsiotas]

Very good! Nice work Vitaly! I have one minor question that I describe here: #648