add Tagline

Illarion in a nutshell. No change in lay-out required. Above the header
so it doesn't interfere with the logo on a small resolution. Will help
potential players see what Illarion is about without reading the entire
blob of homepage text (people usually don't stay on a webpage for longer
than 10 seconds). The German version uses "mit Roleplay-Enforcement"
because it's less stiff and easier to search for than "mit dem
Schwerpunkt Rollenspiel"
Merge branch 'master' of https://github.com/mamoru/Illarion-Website
tagline German

mit echtem Rollenspiel
#7684 - add instructions for rss news feed
Refactor highscores
Implement new marker stone encoding
Fix English title for marker stone highscore
Replace outdated project page with current vision
Add monthly highscore
Added monthly highscore generation to the homepage cronjob
Format of highscores improved