Giant VMM merge, still need to compile it and fix llfloatermarketplacelistings

Merge VMM up to change 187902d9c4afd2990acddeb964c928179a52d189

mAllowWear=>mAllowOpen (should probably just remove this altogether though
inventory_panels now accept the "show_root_folder", "allow_drop_on_root", "allow_open", and "use_marketplace_folders" attributes.

Other stuff in this commit:
LLPanelInjector~
Sync lltooldraganddrop to alchemy
Sync notifications up with alchemy
Reorganize notifications some, to better merge with upstream
Remove duplicate InventorySortOrder in settings map
There's a bit of a weird folderview merge mixed into here, I wouldn't trust it, but this thing is so god damn tangled I can't go back now~

Wouldn't have been possible without help from Shyotl and music by Amanda Palmer

indra/llui/llpanel.cpp

@@ -441,8 +441,31 @@ LLView* LLPanel::fromXML(LLXMLNodePtr node, LLView* parent, LLUICtrlFactory *fac
 	std::string name("panel");
 	node->getAttributeString("name", name);
 
-	LLPanel* panelp = factory->createFactoryPanel(name);
+	std::string class_attr;
+	node->getAttributeString("class", class_attr);
+
+	LLPanel* panelp = NULL;
+
+	{
+		if(!class_attr.empty())
+		{
+			panelp = LLRegisterPanelClass::instance().createPanelClass(class_attr);
+		}
+
+		if (!panelp)
+		{
+			panelp = factory->createFactoryPanel(name);
+			/* Singu TODO: Future?
+			llassert(panelp);
+
+			if (!panelp)
+			{
+				return NULL; // :(
+			}*/
+		}
+	}
 	LL_RECORD_BLOCK_TIME(FTM_PANEL_CONSTRUCTION);
+
 	// Fall back on a default panel, if there was no special factory.
 	if (!panelp)
 	{