add option to toggle clear map before loading

js/gpxedit.js

@@ -461,7 +461,9 @@ function loadFile(file){
     }
     var url = OC.generateUrl('/apps/gpxedit/getgpx');
     $.post(url, req).done(function (response) {
-        clear();
+        if ($('#clearbeforeload').is(':checked')){
+            clear();
+        }
         if (response.gpx === ''){
             alert('The file does not exist or it is not a gpx');
         }

templates/gpxcontent.php

@@ -25,7 +25,12 @@ p($_['gpxedit_version']);
     <hr/>
     <h2 id="loadtitle">Load <b id="loadoptiontoggle"><i class="fa fa-expand"></i></b></h2>
     <div id="loaddiv" style="display:none;">
-        <p>Select a gpx file to load it on the map</p><br/>
+        <p>Select a gpx file to load it on the map</p>
+        <div>
+            <input type="checkbox" id="clearbeforeload"></input>
+            <label for="clearbeforeload">Clear map before loading</label>
+        </div>
+        <br/>
         <div id="loadtree"></div>
     </div>
     <hr/>