vertex format table in newMesh uses the same fields as newBuffer.

Deprecate (but don't remove) the old {name, type, elementcount} vertex format style. The new style is {name=attributename, format=dataformat}.

src/common/deprecation.h

@@ -36,6 +36,7 @@ enum APIType
 	API_CALLBACK,
 	API_FIELD,
 	API_CONSTANT,
+	API_CUSTOM,
 	API_MAX_ENUM
 };