update 20230820-0227

fixed bug. problem:

• tiles were flipping immediately,
• this caused disconnect between flipping action and player moving onto tile later
• also would spawn aliens and then they would move across board before you could arrive
• also just makes sense you need to be next to it to flip it (can't flip it from across map)
• also all this showed that too much decision-making was being made in the "click" event, rather than in the movement code

solution:

• moved the decision-making around tile flip into the player movement code: decision's about flipping and then moving onto it made once player is about to move onto that tile