species static - first prototype

[Maurizio Cimadamore]

Hi,
I've pushed compiler and runtime support for the species static feature. 
More details on the prototype are available in the writeup sent to the 
valhalla-spec-experts mailing list [1]. This is a very early 
implementation effort and it will likely contain many issues. Please 
share your experience on the usage of such feature.

Cheers
Maurizio

[1] - 
http://mail.openjdk.java.net/pipermail/valhalla-spec-experts/2016-May/000148.html