rotate180() {
			const width = this.getWidth();
			const height = this.getHeight();
			let topRow = new BitArray(width);
			let bottomRow = new BitArray(width);
			for (let i = 0, length = Math.floor((height + 1) / 2); i < length; i++) {
				topRow = this.getRow(i, topRow);
				bottomRow = this.getRow(height - 1 - i, bottomRow);
				topRow.reverse();
				bottomRow.reverse();
				this.setRow(i, bottomRow);
				this.setRow(height - 1 - i, topRow);
			}
		}
Modifies this {@code BitMatrix} to represent the same but rotated 180 degrees