Allow components to individually subscribe/unsubscribe to messages,
instead of statically subscribing the entire component type. Use this
for most Interpolate/RenderSubmit messages, to avoid the performance
cost of passing those messages to a large number of components that will
just ignore them anyway.
On Azure Coast this reduces total time per frame by about 30% on a
CPU-bound system.
This was SVN commit r15400.
Ykkrosh
d936bde74a