Get tile URL from map servers
getTileURL = function(x,y,z,t) {return "http://emap"+((x+y)%4)+".mapabc.com/mapabc/maptile?v=w2.99&x="+x+"&y="+y+"&zoom="+(17-z);};
getTileURL = function(x,y,z,t) {return "http://emap"+((x+y)%4)+".mapabc.com/mapabc/maptile?v=w2.99&x="+x+"&y="+y+"&zoom="+(17-z);};