Corrected access protection of MovePlayer

Tests still pass. Phew!
Test that the player gets to the board edge - still green.

Bonus test, just in case an off-by one foils the edge+1 test that
I'm about to write.
Failing test for North edge limit - Red
Failing test for Pattern one end game. - Red
Corrected test output (stop at edge)

while working on code to meet spec.
Delay in commits following dinner :-)
Prevent moving past edge of board, one failure left - nearly green
Stub turn left/right methods and calls. Still red.
Implemented TurnLeft/Right - still red

Now calls to turn succeed but not moving in x direction yet.
Doc update, plus notes about the player vs game state management
Fix increments of direction for East/South/West - tests pass - Green

Wadda you know, the unit tests found an omission in even this simple project :-)