Fix for configure attempting to link boost_system even with boost 1.49 or earlier.
Merge branch 'master' into hotfix/boost1.49-boost_system
Merge branch 'master' into hotfix/boost1.49-boost_system
fix typo in configure.ac
Merge branch 'hotfix'
minor fixes in dithering code
Merge pull request #1 from POV-Ray/master

resync in LeForgeron with Povray-master