vigraraw

This is a fork of https://github.com/ukoethe/vigra
It is a crude attempt at using https://github.com/LibRaw/ for import of images through vigra.
I don't expect to clean it up enough myself to make it a generally useful replacement for vigra.
I am aiming to make it good enough to cover features I am adding to https://sourceforge.net/projects/huginplusplus/