Updated the Mimicry reimplementation

Mimicry is now a proud member of ABILITYEFFECT_ON_TERRAIN.

Misc. changes:
-Ditched the dependency on and usage of gBattlerAttacker for the effects inside ABILITYEFFECT_ON_WEATHER and ABILITYEFFECT_ON_TERRAIN.
-Made Cmd_switchineffects activate ABILITYEFFECT_ON_TERRAIN to take into account overworld weather-induced field terrains.
-Updated the text strings printed by the battle scripts inside the aforementioned AbilityBattleEffects caseIDs.
-Removed constant label of unused VARIOUS_TRY_TO_APPLY_MIMICRY which I forgot about.
-Updated ChangeTypeBasedOnTerrain, partly as a result of the aforementioned changes but also for optimization purposes.
 -There was never a reason to establish an empty scope, or to use GET_MOVE_TYPE and the variables that complemented it.
-Removed case ABILITY_QUARK_DRIVE from AbilityBattleEffects' case ABILITYEFFECT_ON_SWITCHIN.

include/battle.h

@@ -192,6 +192,7 @@ struct SpecialStatus
     u8 dancerUsedMove:1;
     u8 dancerOriginalTarget:3;
     // End of byte
+    u8 terrainAbilityDone:1;
 };
 
 struct SideTimer