getPiskel = function (color, rows, cols) {
    var grid = [];
    for (var i = 0 ; i < rows ; i++) {
      grid[i] = [];
      for (var j = 0 ; j < cols ; j++) {
        grid[i][j] = color;
      }
    }
    return createPiskelFromGrid(grid);
  }
Simple helper to create a monochrome sprite for the provided color,
number of rows and columns.