Add 'plantlike_rooted' drawtype

Useful for underwater plants.
Node consists of a base cube plus a plantlike extension that can pass through
liquid nodes above without creating air bubbles or interfering with liquid flow.
Uses paramtype2 'leveled', param2 defines height of plantlike extension.

src/script/cpp_api/s_node.cpp

@@ -47,6 +47,7 @@ struct EnumString ScriptApiNode::es_DrawType[] =
 		{NDT_FIRELIKE, "firelike"},
 		{NDT_GLASSLIKE_FRAMED_OPTIONAL, "glasslike_framed_optional"},
 		{NDT_MESH, "mesh"},
+		{NDT_PLANTLIKE_ROOTED, "plantlike_rooted"},
 		{0, NULL},
 	};