Correct ZXCapture setTorch:.

Fixes #95
Fix CGImageRef leak in ZXImage.

Fixes #96
Fix example apps
Start and stop capture sessions in background
Improve performance of BarcodeScanner

Initialize the scanner in viewDidLoad, and set/clear the delegate in the
appearance methods.
If ZXMultiFormatWriter is given a format it can't handle, set an NSError
Fixes a potential out of range error
Ported r2720 from ZXing

Original commit message: "Comment out unused encoder code (per Frank
Yellin)"
Update ZXCapture.m

Changed from 'assign' to 'strong' to fix problem where we're assigning retained object to unsafe and unretained variable.
Update ZXPDF417HighLevelEncoder.m

fix bug: if continuous digit count is greater than thirteen, encode will failure, result cannot be decode again.
Update ZXAztecWriter.m

fit output image size to input width & height
Separate unit and blackbox tests into different targets

By default both sets of tests will still run, but this makes it easier
to run just one set of tests.
Fixed possible crashes when Modal ViewControler conforms to ZXCaptureDelegate.
Version bump: 2.2.3
Fix project file
Update OS X Unit Tests name
Specify 64-bit iOS support in the project file
Cast possibly ambiguous invocations of 'count'. Fixes #113
Update project file and schemes for Xcode 5
Parallelised luminance conversion routine and also converted floating point to integer math. Difference in result from FP math is on average less than 1 level. Decent performance boost =)