multiple pass sprite

on ShaderSprite2.cpp
Merge pull request #6767 from ricardoquesada/sprite_multiple_pass

multiple pass sprite
uniform sampler CC_Texture0 MUST NOT be defined on shaders

since it is a built-in.
Built-in uniforms MUST NOT be defined on shaders.
Basically all CC_ uniforms must be defined by cocos2d-x
Merge pull request #6768 from ricardoquesada/uniform_texture_0

uniform sampler CC_Texture0 MUST NOT be defined on shaders
default value is 0.5 for interpolation
Merge pull request #6769 from ricardoquesada/interpolate_fix

default value is 0.5 for interpolation
Does not crash on Mac if the .ttf file is not found
Merge pull request #6770 from ricardoquesada/label_fixes

Does not crash on Mac if the .ttf file is not found