Add onLocationChange.fitView config option

It defaults to false now, which is a change - this seems like a sensible
choice though. I can see how it would be annoying to have the map change
while looking at it just because *something* moved.

Fixes #41.

src/config.js

@@ -67,6 +67,7 @@ const DEFAULT_CONFIG = {
     url: "https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png",
   },
   onLocationChange: {
+    fitView: false,
     reloadHistory: false,
   },
   primaryColor: "#3f51b5",

src/views/Map.vue

@@ -232,7 +232,9 @@ export default {
   },
   watch: {
     lastLocations() {
-      this.fitView();
+      if (this.$config.onLocationChange.fitView) {
+        this.fitView();
+      }
     },
     filteredLocationHistory() {
       this.fitView();