fix bug for renderTexture created which is bigger than screen size
using pointer instead of Director::getInstance() in RenderTexture
readd wp8 code which is removed by accident
Improved directory structure
Adds Apache2 license to GamePlay3d files
Fix ParticleSystem yCoordFlipped bug.
fix indent
Merge pull request #6521 from boyu0/particle_yCoordFlipped_bug

Fix ParticleSystem yCoordFlipped bug.
[ci skip]
Merge pull request #6512 from dabingnn/v3_renderTextureBug

V3 render texture bug
refactor normalize in Vector2
remove some cumbersome struct keyword
refactor normalize in Vector3
refactor normalize in Vector4
refactor normalize in Quaternion
Merge branch 'v3' into v3_refactor_normalize
getNormalize->getNormalized
inverse and conjugate for quaternion
inverse and conjugate, negate for matrix
Merge pull request #6523 from dabingnn/v3_refactor_normalize

V3 refactor normalize