Add `Json.mapOfFrom(Class)` to support binding POJO-valued maps

[ocind]

Hi 'm wondering if Map<String, POJO> deserialization is currently supported by jackson-jr.
As far as I see, there is only mapFrom which returns Map<T,Object>

[cowtowncoder]

Currently it is not supported and references to Map mean "untyped".

But since there actually is listOfFrom(), we could quite easily have mapOfFrom() to do this -- would that make sense? I think I could probably add this in 2.10, to be available relatively soon.

[ocind]

@cowtowncoder whoa! that's really fast! Thank you @cowtowncoder for the awesome work!!!

[cowtowncoder]

Lucky timing :)

But thank you for pointing out the missing part -- it happened to be easy to add, too, given existing listOfFrom(). I am happy to get a few improvements in 2.10, to make jackson-jr much more useful: now one can add custom ValueReader s and ValueWriters too, opening door to 3rd party datatypes as well.