Given the start and end coordinates, return all the coordinates lying
on the line formed by these coordinates, based on Bresenham's algorithm.
http://en.wikipedia.org/wiki/Bresenham's_line_algorithm#Simplification
@param {number} x0 Start x coordinate
@param {number} y0 Start y coordinate
@param {number} x1 End x coordinate
@param {number} y1 End y coordinate
@return {Array.<Array.