feat: zones - restore layer

main.js

@@ -1535,8 +1535,7 @@ function undraw() {
   viewbox
     .selectAll("path, circle, polygon, line, text, use, #texture > image, #zones > g, #armies > g, #ruler > g")
     .remove();
-  document
-    .getElementById("deftemp")
+  byId("deftemp")
     .querySelectorAll("path, clipPath, svg")
     .forEach(el => el.remove());
   byId("coas").innerHTML = ""; // remove auto-generated emblems

modules/ui/layers.js

@@ -181,6 +181,7 @@ function restoreLayers() {
   if (layerIsOn("toggleIce")) drawIce();
   if (layerIsOn("toggleEmblems")) drawEmblems();
   if (layerIsOn("toggleMarkers")) drawMarkers();
+  if (layerIsOn("toggleZones")) drawZones();
 
   // some layers are rendered each time, remove them if they are not on
   if (!layerIsOn("toggleBorders")) borders.selectAll("path").remove();