resolve compile failure on bad C++ standard library value

perhaps the compiler default isn't valid when building on Xcode 4.6 or it needs to be set explicitly.
Merge pull request #287 from pizthewiz/multitouch_sample

resolve OS X compile failure on bad C++ standard library value
Added bool Timeline::empty() method.

Mirrors std::container empty methods and is a useful counterpart
to the existing getNumItems(). Makes it easy to wait for animations
to complete before processing certain actions:
// e.g. in an update loop, don't process things if animating:
if( mSpecialTimeline.empty() )
{
 processSpecialItems();
}
Merge pull request #288 from sansumbrella/timeline_additions

Added bool Timeline::empty() method.
Minor fix to Box2D CinderBlock
Build fix for MotionBasic sample