Remove unused/undocumented component.onModelChange

[tsjoberg]

[tsjoberg]

@markijbema @clayallsopp not sure what you envision for deprecation warning console.warn ? Or actually want me to check for implementation of onModelChange and call forceUpdate instead with console warning?

[tsjoberg]

Fixes https://github.com/clayallsopp/react.backbone/issues/40

[markijbema]

Yes, I think that would be best, and then remove it in a version a few months later. I'm not sure what react itself uses, but it seems to have some deprecation warning messaging, maybe you could plug into that?

Problem with just removing is that if somebody uses it, it may fail very subtly. For instance if you do increment of a counter, and then forceUpdate, the counter won't update, but everything seems to work, so this might silently introduce bugs.