bulb_nd: long exposure / ND filter utilities
Created originally on Bitbucket by dmilligan (David Milligan)
Was already merged in Bitbucket before import, marked as merged by the import user
http://www.magiclantern.fm/forum/index.php?topic=12846.msg123830
http://www.magiclantern.fm/forum/index.php?topic=12960.msg125180