- redid autoload handler and resource file filtering to use the newly defined method with multi-part names.

As a result the old 'Group' property could be removed and all other means to get a section name were disabled.
As an example, if the code gets 'doom.doom2.commercial' it will use the following sections in this order:

global.autoload
doom.autoload
doom.doom2.autoload
doom.doom2.commercial.autoload.

src/d_iwad.cpp

@@ -138,12 +138,6 @@ void FIWadManager::ParseIWadInfo(const char *fn, const char *data, int datasize)
 					sc.MustGetString();
 					iwad->Autoname = sc.String;
 				}
-				else if (sc.Compare("Group"))
-				{
-					sc.MustGetStringName("=");
-					sc.MustGetString();
-					iwad->Group = sc.String;
-				}
 				else if (sc.Compare("Config"))
 				{
 					sc.MustGetStringName("=");