Improve detector logic to throw out false positive finder patterns in a more reasonab...

Improve detector logic to throw out false positive finder patterns in a more reasonable manner. Current logic didn't quite achieve its goal in some corner cases and needed rethinking and some simplification. Fixes a reported failure from the group list. Net change in passed test cases is -1 otherwise (for 270 degree rotation -- not vital) so I consider it a net tiny win.

git-svn-id: http://zxing.googlecode.com/svn/trunk@1039 59b500cc-1b3d-0410-9834-0bbf25fbcc57