TargetBlock: Implement

[np-eazy]

A TargetBlock is a square-shaped group of cells at some center location, which must be filled before it grows too large.

• x0: x upper left

• y0: y upper left

• x1: x lower right

• y1: y lower right

• iterations: number of block placements this TargetBlock has lived

• iterationsToGrowth: number of iterations left until the next time it grows

• ticks: number of ticks this TargetBlock has lived

• new TargetBlock(x0, y0, x1, y1): A TargetBlock starts at size 2x2, but has the option to start at whatever size. Don't spawn within 2 blocks of the edge.

• checkClear(): A TargetBlock is cleared when all the blocks inside it are solid.

• grow(): Every 4N block placements, the TargetBlock grows by moving x0, y0 up and left, and x1, y1 down and right. N starts at 1 and goes up by 0.5

• checkGameOver(): If x0, y0 or x1, y1 ever leave the game bounds, we can trigger a gameOver flag

[np-eazy]

Actually it is a better game design choice to have TargetBlocks start of at 3x3.

[np-eazy]

At the rate they are spawning, the TargetBlocks in this commit are too difficult for a normal game. The point of this issue was just to get the logic in though, and we can always change the parameters and tweak the rules/logic in another ticket focused on the game design per se.