Make TextureVariable references align with game behaviour (#525)

While the current implementation of reference handling in
this class was the correct way to go (only handling
texture names starting with # as references), the game is
happy to accept references without a leading hashtag, since
it just chops it off and continues on the same code path
regardless.

This commit makes the reference handling in BlueMap align
with this behaviour, potentially allowing "broken" models
to render as they do in game.

This method works for reference resolving, since if a string
passed into the texture field contains a ':' then it must be
a namespaced key, and if it contains a '/' it has to be a
resource key, because the 'minecraft' namespace is implied
in these cases. The other way around, if someone were to pass
in a string like 'oak_planks', it is safe to assume it is a
reference, since the implied resource key would be
'minecraft:oak_planks', but textures aren't at the root level
in that namespace.

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/resources/resourcepack/blockmodel/TextureVariable.java

@@ -140,13 +140,16 @@ public void write(JsonWriter out, TextureVariable value) throws IOException {
         public TextureVariable read(JsonReader in) throws IOException {
             String value = in.nextString();
             if (value.isEmpty()) throw new IOException("Can't parse an empty String into a TextureVariable");
+
             if (value.charAt(0) == '#') {
                 return new TextureVariable(value.substring(1));
             } else {
+                if (!(value.contains(":") || value.contains("/"))) {
+                    return new TextureVariable(value);
+                }
+
                 return new TextureVariable(new ResourcePath<>(value));
             }
         }
-
     }
-
 }