unsupported on new macOS)

Sprout from master 2018-01-11 16:54:57 UTC Matthew Webster <mwebster@fmrib.ox.ac.uk> 'sh to bash'
Cherrypick from newnew 2014-12-11 15:04:04 UTC Matthew Webster <mwebster@fmrib.ox.ac.uk> '2014 Candidate checkin':
    Makefile
Delete:
    doc/index.html

Bugfix to viena_quant - non existent environment variables were being used when generating "<IMG SRC="..."/> tags. The siena, viena_quant and viena_createpng scripts are incredibly tightly coupled, and could do with some refactoring.