Preserve components between routes

[alexkirsz]

Currently, handler components are given a key relative to their route's path, which means that you can't use react's diff algorithm between handlers.

However, I'd like to preserve some components between routes. In my case, a sidebar that only changes some of its content between two routes.

[alexkirsz]

Whelp, duplicate of #97.

[ryanflorence]

yeah, this is changing asap. for now you can <this.props.activeRouteHandler key="blah"/> to use the same key between sibling routes.

[gaearon]

I have

<this.props.activeRouteHandler key="https://github.com/rackt/react-router/issues/225" />

:-)

[ryanflorence]

btw: #229 will cut a release today if I get enough time to document all the recent changes.