Merged requested to merge branch/jit_hint_docs into branch/default
Created originally on Bitbucket by vext01 (Edd Barrett)
I decided to add my notes about a cuople of jit hints to rlib/jit.py. Hopefully this will serve as a useful reference.
@fijal and @cfbolz have critiqued and earlier version of this, but no-one has seen my description of @jit.promote. Please check carefully.