Add convenient methods for centering independently each axis

-keepHorizontallyCentered[WithPriority:]
-keepVerticallyCentered[WithPriority:]
Turn on 64-bit
Added and completed documentation
Improve comments and structure of UIView category header
Change declarations of attributes to @property

Now the documentation comments are diplayed propertly when used with dot
syntax.
Change declarations of attributes to @property for NSArray too

Now the documentation comments are diplayed propertly when used with dot
syntax.
Improve comments and structure of NSArray category header
Set Example to run in 64-bit
Backward compatibility with iOS 6

Using compile-time check for iOS 7 SDK and use iOS 6 runtime fallbacks.
Version bump 1.2.2
Some nice Tint Color
New Example with Dynamic Text
Add comments for Tiles example with number of constraints created – 334
Icon and launching images for Example
Fix pragma typo