Test for template with a collection of images tileset

tests/test_data/map_tests/template/map.json

@@ -19,6 +19,12 @@
                  "template":"template_tile.json",
                  "x":46.3682110303692,
                  "y":112.993321292057
+                }, 
+                {
+                 "id":5,
+                 "template":"template_tile_image.json",
+                 "x":116,
+                 "y":145
                 }],
          "opacity":1,
          "type":"objectgroup",
@@ -27,7 +33,7 @@
          "y":0
         }],
  "nextlayerid":3,
- "nextobjectid":4,
+ "nextobjectid":6,
  "orientation":"orthogonal",
  "properties":[
         {
@@ -61,12 +67,16 @@
          "value":"Hello, World!!"
         }],
  "renderorder":"right-down",
- "tiledversion":"1.6.0",
+ "tiledversion":"1.7.1",
  "tileheight":32,
  "tilesets":[
         {
          "firstgid":1,
          "source":"tileset.json"
+        }, 
+        {
+         "firstgid":49,
+         "source":"tileset_single_image.json"
         }],
  "tilewidth":32,
  "type":"map",