feature request: add favicon

[practik]

For those of us using kiwix-js on desktop browsers, it would be helpful to have the favicon showing on the Kiwix tab. I know this was mentioned in passing at #280 (comment), but since that issue is really about the window title, I figured the favicon should have its own issue.

Kiwix 2.3.0 on Firefox 61.0.1 on macOS

[mossroy]

That makes sense. It's probably easy to do.
We currently have an obsolete www/favicon.ico file (with an evopedia logo instead of kiwix), that should be removed, and replaced by some HTML link rel="icon" tags in the header of www/index.html, pointing to the existing PNG icons in www/icons

[mossroy]

It might also be worth adding link rel="apple-touch-icon" tags for Apple devices. And maybe the meta name="msapplication-*" ones plus the browserconfig.xml file?
http://faviconit.com seems to give some templates

[Jaifroid]

But would Apple devices use this app? Wouldn't they install the Kiwix app from their respective stores? If we are going to be fully inclusive, we would probably need to do everything on this cheat sheet:

https://github.com/audreyr/favicon-cheat-sheet

But it may be over the top!

[mossroy]

This guide handles very old browsers that we do not even support : I agree with you it's no use adding hacks in our code for them.