Hide Helper blocks when importing libraries

snap.html

@@ -20,7 +20,7 @@
         <script src="src/threads.js?version=2022-02-22"></script>
         <script src="src/objects.js?version=2022-02-22"></script>
         <script src="src/scenes.js?version=2021-11-24"></script>
-        <script src="src/gui.js?version=2022-02-22"></script>
+        <script src="src/gui.js?version=2022-02-23"></script>
         <script src="src/paint.js?version=2021-07-05"></script>
         <script src="src/lists.js?version=2022-02-07"></script>
         <script src="src/byob.js?version=2022-02-17"></script>

src/gui.js

@@ -9118,7 +9118,7 @@ LibraryImportDialogMorph.prototype.hasCached = function (key) {
 };
 
 LibraryImportDialogMorph.prototype.cacheLibrary = function (key, blocks) {
-    this.libraryCache[key] = blocks ;
+    this.libraryCache[key] = blocks;
 };
 
 LibraryImportDialogMorph.prototype.cachedLibrary = function (key) {
@@ -9176,6 +9176,8 @@ LibraryImportDialogMorph.prototype.displayBlocks = function (libraryKey) {
 
     SpriteMorph.prototype.allCategories().forEach(category => {
         blocksList.forEach(definition => {
+            if (definition.isHelper) {return; }
+
             if (definition.category !== category) {return; }
             if (category !== previousCategory) {
                 y += padding;

sw.js

@@ -1,4 +1,4 @@
-var snapVersion = '7.2.1',
+var snapVersion = '7.3 - dev',
     cacheName = 'snap-pwa',
     filesToCache = [
         'snap.html',