Finish and polish new_game.c

Only one function is left undocumented. I tried to go into the assembly
to at least name it, but it clears fields in the save block that aren't
even documented yet.

include/secret_base.h

@@ -24,6 +24,7 @@ void sub_80EBB28(void);
 void WarpIntoSecretBase(const struct MapPosition *position, const struct MapEvents *events);
 bool8 sub_80E909C(void);
 void sub_80EB218(void);
+void ResetSecretBases(void);
 
 // SetCurrentSecretBaseFromPosition
 void sub_80E9608(const struct MapPosition *position, const struct MapEvents *events);
@@ -33,4 +34,5 @@ void sub_80E8BC8(void);
 void sub_80E8D4C(void);
 void EnableBothScriptContexts(void);
 
+
 #endif //GUARD_SECRET_BASE_H