Return GetNames languages, to avoid hardcoded language lists in callers

This makes the code cleaner and also leads to some user-visible changes:

The wx game properties will no longer let the user
select WAD languages that don't have any names.

The Qt game list will now display names using the languages
set in the configuration instead of always using
English for PAL GC games and Japanese for WADs.

If a WAD doesn't have a name in the user's preferred language,
English is now selected as a fallback before Japanese.

Source/Core/DiscIO/VolumeCommon.cpp

@@ -2,6 +2,7 @@
 // Licensed under GPLv2
 // Refer to the license.txt file included.
 
+#include <map>
 #include <string>
 #include <vector>
 
@@ -104,7 +105,7 @@ std::string IVolume::GetName() const
 	if (names.empty())
 		return "";
 	else
-		return names[0];
+		return names.cbegin()->second;
 }
 
 }