Merge pull request #1986 from dingpinglv/Iss3546_BakeLayer

Fixed #3546: fixed a bug about bake layer that its position is incorrect when cc.view scaled.
issue #5685: refactor create functions of ParticleExamples
Merge pull request #1987 from joshuastray/use_new_in_sample

issue #5685: refactor create functions of ParticleExamples
issue #5685: fix LayerMultiplex ctor bug
issue #5685: fix LayerMultiplex.create
Merge pull request #1990 from joshuastray/use_new_in_sample

issue #5685: fix LayerMultiplex ctor bug
[Fix] - Check empty string for textureData

Previous way which is used to check string is empty or null is not right because in case of string is empty the expression always false.
Merge pull request #1992 from MQuy/patch-2

[Fix] - Check empty string for textureData
Fixed #3546：fixed a bug of cc.LayerGradient, its drawing is incorrect when cc.view's scale doesn't equal 1.