Version 5.6.0

New features/improvements:

• added a new piece theme named companion
• added players lifetime score in game screen
• added a new about page to explain lichess
• added score to the piece cemetery
• added votes to puzzles

Bux fixes:

• fixed new puzzle spamming bug that could add incoherent rating
• fixed chat messages not properly loaded
• fixed broken links to lichess.org
• [android] hardware button control media volume while using the app