allow same file to be imported twice

js/importer.js

@@ -36,6 +36,7 @@ function initImporter(globals){
         var name = extension[0];
         extension = extension[extension.length - 1];
         var reader = new FileReader();
+        $(e.target).val("");
 
         if (extension == "txt") {
             reader.onload = function () {

js/pattern.js

@@ -436,7 +436,7 @@ function initPattern(globals){
         if (_weededVertices.length > 0){
             console.log(_weededVertices);
             globals.warn("Some vertices are not fully connected, try increasing vertex merge tolerance");
-            // return;
+            return;
         }
 
         removeCombinedFromSet(combined, outlines);