Fix mapgen: correct the type of the object to place.

Loading the data fails as there is no *terrain* f_mutpoppy, only a furniture of that type.

data/json/mapgen/teashop.json

@@ -186,9 +186,9 @@
                { "x": 4, "y": 4, "signage": "The Red Dragon Tea Shop" }
            ],
            "set": [
                { "point": "terrain", "id": "f_mutpoppy", "x": [ 0 , 23 ], "y": [ 19, 23 ], "repeat": [ 4, 9 ] },
                { "point": "furniture", "id": "f_mutpoppy", "x": [ 0 , 23 ], "y": [ 19, 23 ], "repeat": [ 4, 9 ] },
                { "point": "terrain", "id": "t_shrub", "x": [ 0 , 23 ], "y": [ 19, 23 ], "repeat": [ 4, 9 ] },
                { "point": "terrain", "id": "f_chamomile", "x": [ 0 , 23 ], "y": [ 19, 23 ], "repeat": [ 4, 9 ] }
                { "point": "furniture", "id": "f_chamomile", "x": [ 0 , 23 ], "y": [ 19, 23 ], "repeat": [ 4, 9 ] }

            ],
            "place_items": [