adds preferences, updatePreferences and getPreferences to User
moves stop updating challenge list call into the 'game page exists' part of /game/id route handler in Lightsquare
Revert "tweaks history style - simplifies and reduces width"

This reverts commit 79017500f619c0245ffe280464a60f8f585446da.
synchronises selected history move with game state in GamePage

adds getLastMove method to Game