Button icons
Refactoring JurorDetails

Removed TournamentSolver reference from JurorDetailsSkin and some
rendering logic, making it much more simple.
Pulling solver out of groups + related refactoring

- changed JurorRow into SeatInfo
- locking kept working but needs serious cleanup
Fix NPE whe constructing SeatInfo for empty seats
Synchronize solutionChanged() to avoid ConcurrentModificationException