Support string as accessor?

[bclinkinbeard]

Since plucking off a single property is likely a very common use case, it would be nice to support simply passing a string so that d3.set(stuff, 'name') would be equivalent to d3.set(stuff, x => x.name).

I'd be happy to submit a PR if this is a feature you'd accept.

[mbostock]

Sorry, but I do not want to provide this convenience API; I’d rather favor parsimony and use x => x.name.