Sub-folder sorting

Patches were sorted correctly as were categories, but in order to
enable sub-folders I construct an explicit child list in
categories. I do that before the patch sort and traverse it
at menu build time. That category list requires a sort to
display correctly.

Fixes surge-synthesizer#481

src/common/SurgeStorage.cpp

@@ -350,6 +350,7 @@ void SurgeStorage::refreshPatchlistAddDir(bool userDir, string subdir)
    ** scanning for names; setting the 'root' to everything without a slash
    ** and finding the parent in the name map for everything with a slash
    */
+
    std::map<std::string,int> nameToLocalIndex;
    int idx=0;
    for (auto &pc : local_patch_category)
@@ -368,6 +369,23 @@ void SurgeStorage::refreshPatchlistAddDir(bool userDir, string subdir)
        }
    }
 
+   /*
+   ** We need to sort the local patch category child to make sure subfolders remain
+   ** sorted when displayed using the child data structure in the menu view.
+   */
+
+   auto catCompare =
+       [this](const PatchCategory &c1, const PatchCategory &c2) -> bool
+       {
+           return _stricmp(c1.name.c_str(),c2.name.c_str()) < 0;
+       };
+   for (auto &pc : local_patch_category)
+   {
+       std::sort(pc.children.begin(), pc.children.end(), catCompare);
+   }
+
+
+
    /*
    ** Then copy our local patch category onto the member and be done
    */