update window size after constrainFrameRect is called
Merge pull request #401 from nselikoff/osx-fix-constrained-window-size

Update window size after constrainFrameRect is called
Querying window size after setWindowSize() to determine post-constraint size on Mac
Adding missing libpng16 for Cairo Mac, and updating samples to match
Fixing issue with MatrixAffine2::rotateCopy methods

Before that, the following would not compile due to:
No matching member function for call to 'rotateCopy'

ci::MatrixAffine2f m1;
auto m2 = m1.rotateCopy(M_PI * 0.5f);
auto m3 = m1.rotateCopy(M_PI * 0.5f, ci::Vec2f(100, 200));
Merge pull request #406 from arielm/fix/MatrixAffine2

Fixing issue with MatrixAffine2::rotateCopy methods