new mutations + plant part data structure simplified

entities/plants/scripts/plant_mutation/humide_mutation.gd

@@ -0,0 +1,23 @@
+extends PlantMutation
+class_name HumideMutation
+
+func get_icon() -> Texture:
+    return preload("res://common/icons/shield.svg")
+
+func get_mutation_id() -> String:
+    return "HUMIDE"
+
+func get_mutation_name() -> String:
+    return tr("HUMIDE")
+
+func get_mutation_description() -> String:
+    return tr("HUMIDE_EFFECT_TEXT").format({
+        "score_icon": Text.bbcode_icon(Plant.SCORE_ICON),
+        "score_multiplier": get_score_multiplier() + 1.,
+    })
+
+func mutate_score_multiplier(_plant_data: PlantData, multiplier: float) -> float:
+    return multiplier + (get_score_multiplier() if GameInfo.game_data.current_region_data.meteo_type == Meteo.Type.RAINY else 0.0)
+
+func get_score_multiplier()->float:
+    return 0.5 * level