favicon and keywords

I improve the favicon for better compatibility with browsers and devices. Many browsers - operating systems (like windows8 or ios) dont properly display the favicon and have obsessive instructions to make it work. Here the [current report](http://realfavicongenerator.net/favicon_checker?site=mapazonia.org&ignore_root_issues=on)

More info about this topic => https://github.com/audreyr/favicon-cheat-sheet

Added a list of keywords that search engines can deliver better results for anyone looking for related information.