Add torch-like effect to JSRL game

Display.js

var LIGHT_COLOR = { r: 255, g: 128, b: 128 };
var LIGHT_INTENSITY = 0.7;
var MAX_DIST = 8;

// Helper function that calculates a distance
function distance(x1, y1, x2, y2) {
	return Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
}

// Helper function that does blending between two values
function blend(a, b, f) {
	return a*f + b*(1.0-f);
}

module.exports = {
	init: function(game, config){
		// Stripped init
    
		// Shades the tile according to distance from player,
		// giving a kind of torch effect
		var theGame = this.game;
		function doLighting(tile, x, y, time) {
			// console.log("TIME", time)
			var pl;
			try {
				pl = theGame.world.level.player;
			} catch (e) {
				return tile;
			}

			var xr = x - pl.x;
			var yr = y - pl.y;
			if (!pl.canSee(xr, yr) || (xr === 0 && yr === 0)){
				return tile;
			}
			
			// Calculate a pulsating animation value from the time
			var anim = time / 1000.0;
			anim = Math.abs(anim - Math.floor(anim) - 0.5) + 0.5;
			var d = distance(pl.x, pl.y, x, y);
			// No shading if the tile is too far away from the player's "torch"
			if (d >= MAX_DIST) return tile;
			// We will create a new instance of ut.Tile because the tile
			// passed in might be (and in this case is) a reference to
			// a shared "constant" tile and we don't want the shader to
			// affect all the places where that might be referenced
			var shaded = new ut.Tile(tile.getChar());
			// Calculate a blending factor between light and tile colors
			var f = (1.0 - (d / MAX_DIST)) * LIGHT_INTENSITY * anim;
			// Do the blending
			shaded.r = Math.round(blend(LIGHT_COLOR.r, tile.r, f));
			shaded.g = Math.round(blend(LIGHT_COLOR.g, tile.g, f));
			shaded.b = Math.round(blend(LIGHT_COLOR.b, tile.b, f));
			return shaded;
		}
		this.eng.setShaderFunc(doLighting);
		var that = this;
		window.setInterval(function() { that.refresh(); }, 50); // Animation
	}
 }

This integrates the torch-like shader from unicodetiles.js https://github.com/tapio/unicodetiles.js into the Display object of JSRL https://github.com/slashman/jsrl