Image::flipVertically(), Image::flipHorizontally() optimizations.
Minor improvements in sf::Window and sf::RenderWindow documentation
Minor improvements in sf::Ftp documentation
Optimized sf::Listener with a cache

Two optimizations:
- Get functions return locally stored value
- Set functions call OpenAL only if value has changed
Exposed up vector in sf::Listener API

Closes #545
Output error message in SoundStream when bits are zero

Fixes #529
Made Ftp::sendCommand() public
Minor formatting
Improved Ftp::sendCommand() documentation
Fixed several Doxygen warnings, limited input to *.hpp files
Cached sf::Text attributes

Two optimizations:
- If a value remains the same, nothing happens
- Recompute geometry only before drawing and bound access, not after each set

Closes #413
Fix typos and missing Joystick::
Window::create() now also resets framerate limit

Fixes #371
Fixed disabling key repeat on Linux
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.