Qt: Use Qt's exit routine which returns exec() and allows clean exit.
Some input tweaks and UI utility functions
"Support" override on Symbian (kill it with a #define)
Avoid using override in GCC < 4.7.

Travis has some non-Symbian builds using 4.6.3 and they are failing.
iOS: add GLES 3.0 support
Merge pull request #217 from rock88/master

iOS: add GLES 3.0 support
Fix GLES2 SDL builds.
Support all 'other' GLES platforms. Keep ifdefs consistent between gl_common and gl3 stub.
SDL: Make the code more platform-agnostic and cleaner.
SDL: Enable up to 2 joysticks for everyone.
More cleanup for GL
Switch to libpng17 to resolve NEON issue on iOS + other bug fixes.
Oops. eglext wasn't meant to be there.
Update everything to libpng17 (even atlastool).
make enum identifiers for all pad numbers, add a constant for the max number of pads and add string names for each identifier
Merge pull request #218 from Bigpet/incMaxPad

increase number of named pads
Define MAY_HAVE_GLES3 on all platforms. Tell me if there are any errors on Maemo/Meego or other ARM platforms.
Fix all warnings/errors on Blackberry.
Revert GLES3 headers as they didn't include nvidia extensions.
Remove MAY_HAVE_GLES3
Buildfix Qt5 mobile platforms such as Android.