Add sudokusolver led display & add problem transformations

[eloots]

• Visualize Sudoku solving activity on LEDs 9 and 10
  • Pulse LED 9 for ±15ms:
  • Green when sudoku problem can be handled immediately
  • Blue when problem has to be stashed because solver is busy
  • Red when problem is dropped due to stash buffer full
  • LED 10 is Green during the solving of a sudoku problem
  • Note that this allows to visualize HotSpot optimalisation; On a Raspberry Pi, the first sudoku takes ±1 second to solve. Once steady-state is reached, this drops to ±30 milliseconds.
• The LedStripDriver actor is instantiated separately so that it is accessible by the SudokuSolver actor.
• The SudokuProblemSender actor sends transformed versions of a single Sudoku problem. It renders it into different versions of the problem by rotating, mirroring, transposing, ... it.