Backface culling: Ignore setting in tiledef from old servers.

Outdated servers are always sending tiledefs with culling
enabled no matter what, as the value was previously entirely
ignored.

To compensate, we must (1) detect that we're running against
an old server with a new client, and (2) disable culling for
mesh, plantlike, firelike and liquid draw types no matter what
the server is telling us.

In order to achieve this, we need to bump the protocol version
since we cannot rely on the tiledef version, and test for it
being older. I've bumped the protocol version, although that
should have likely happened in the actual change that introduced
the new backface_culling PR #3578. Fortunately that's only 2
commits back at this point.

We also explicitly test for the drawtype to assure we are not
changing the culling value for other nodes, where it should
remain enabled.

This was tested against various pub servers, including 0.4.13 and
0.4.12.

Fixes #3598

src/nodedef.h

@@ -137,7 +137,7 @@ struct TileDef
 	}
 
 	void serialize(std::ostream &os, u16 protocol_version) const;
-	void deSerialize(std::istream &is);
+	void deSerialize(std::istream &is, bool culling_ignore);
 };
 
 enum NodeDrawType