title: zxing library minimium SDK & core.jar
body: <p>I'm trying to compile the ZxING BarCode scanner, that comes from default for SDK 7.  The problem here, is that I want to compile and test it on a SDK 4 device, so when I change in properties the android version and the target SDK on the ManifestFile a lot of errors appears. Is there a minimum SDK requirement for ZXING? Is there a version of the zxing library for older SDK's?</p>