Settings: Proper priority hierarchy

Remove old defaults system
Introduce priority-based fallback list
Use new functions for map_meta special functions
Change groups to use end tags

Unittest changes:
 * Adapt unittest to the new code
 * Compare Settings objects

src/remoteplayer.h

@@ -140,7 +140,6 @@ public:
 	void onSuccessfulSave();
 
 private:
-
 	PlayerSAO *m_sao = nullptr;
 	bool m_dirty = false;