Convert to ARC

1) modifies all elements to support this project as a standalone ARC example; 2) deletes all "release" statements; 3) deletes all calls to "[super dealloc]"; 4) deletes all "autorelease" statements from the project
*** This ARC version has been successfully tested and integrated with an app of my own ***
Upgrade project file for Xcode 5
FIX import files in sample examples
Fix compiler warnings. Fixes #79
Convert to Modern Objective-C syntax
Convert examples to ARC, fix a few more warnings
Use "strong" and "weak" for properties
Remove @synthesize and local function definitions
Replace unsigned char with int8_t
Example cleanup
Mark ARC as required in the podspec
Remove a possible reference cycle
Fix a memory leak in ZXCapture. Fixes #59
Use an int array over an NSArray in ZXGlobalHistogramBinarizer

Reduces the number of memory allocations performed
Fix a potential memory leak
Run image capture on background queue.

Makes a *huge* difference in UI responsiveness when showing the
scanner at the same time as other UI elements (say a left side
menu ala facebook).
Fix warnings on Mac
Version bump: 2.2.0
Ported r2587 from ZXing

Original commit message: "Add more hints for Aztec encoding"
Ported r2591 from ZXing

Original commit message: "More PDF417 test cases"