Improved coding style of OS X implementation

And fixed some typos.
Fixed a few glitches in the documentation
Fixed unused parameter warnings
Removed support for OS X 10.6 and below
Updated Objective-C implementation to use ARC; removed i386 support
Fixed NSApplication not retaining its delegate
Added some memory autorelease pools and nil'ify attribute
Fixed incorrect symlink in freetype.framework (close #519)
Added support for OpenGL 3.2 context on OS X (close #84)

The Graphics module is not compatible with a core profile on Mac. If
you plan to use it, use OpenGL 2.1 (default).
Updated Xcode templates and cmake script

What's new in the templates:
 - Removed support for 32 bits and gcc
 - Removed useless code
 - Removed custom warnings settings – let Xcode decide with its default values
 - Set default target version to CMAKE_OSX_DEPLOYMENT_TARGET

What's new in cmake script:
 - Added cmake options for archs and deployment target
 - Added minimum requirements checking
Improved documentation for sf::Shape and derived classes
Fixed compile warnings
Added the iOS port
Fixed render buffers not correctly resized on orientation changes
[iOS] Adjusted the code and build files to use Automatic Reference Counting
[iOS] Various adjustements to implementation
Added the Android port
Improved OpenGL error macro

It now supports functions that return values.
Improved OpenAL error macro

It now supports functions that return values.
Adapted the examples for iOS (WIP)