Add ability to load a map file manually

public/index.html

@@ -121,8 +121,12 @@
           <span class="inning-bottom">◒</span>
         </span>
         <button id="show-dialog" type="button">Change map</button>
-        <button id="fullscreen" type="button">Fullscreen</button>
         <button id="download-save" type="button">Save</button>
+        <button id="upload-save" type="button">Load</button>
+        <button id="fullscreen" type="button">
+          <img src="assets/images/icon_full_screen.png" height="12" />
+        </button>
+
         <span style="white-space: nowrap;">
           Prone: <input type="checkbox" id="toggle-prone-counter" />
           <button type="button" class="set-firing-arc" data-size="small">
@@ -197,6 +201,8 @@
       </form>
     </dialog>
 
+    <input type="file" accept="image/svg+xml"/>
+
     <script src="index.js"></script>
     <script src="soldier_record_block.js"></script>
   </body>