More PDF417 changes from Guenther

git-svn-id: http://zxing.googlecode.com/svn/trunk@2708 59b500cc-1b3d-0410-9834-0bbf25fbcc57
More rational sizing of reticle (max size 50% of screen dimension) but also allow larger reticles to accomodate very high res new devices like the S4

git-svn-id: http://zxing.googlecode.com/svn/trunk@2709 59b500cc-1b3d-0410-9834-0bbf25fbcc57