some notes about tiles

README

@@ -121,6 +121,7 @@ https://git.syndicate-lang.org/tonyg/squeak-phone/raw/commit/474960ddc665ed445a1
 
 we need to extend to multiple tiles'-worth of map
 
+
 * get tile for curent lat/long and request overpass data for enough
   surrounding tiles to fill the screen
 
@@ -133,9 +134,8 @@ them if the come up again
 * to get it centred on the cyclist, take the tile fractional part *
   256, and translate the canvas up and left by that amount
 
+* add a cache of [x,y,z] -> polylines so that we don't keep hitting overpass
 
 
-and offset
-by