Pure Texture to Sampled Texture Transform

Adds a transformation step to the post processing step.
Two modes are available:
1) keep
- Keeps samplers, textures and sampled textures as is
2) transform pure texture into sampled texture and remove pure samplers
- removes all pure samplers
- transforms all pure textures into its sampled counter part

Change-Id: If54972e8052961db66c23f4b7e719d363cf6edbd

glslang/Include/Types.h

@@ -1310,6 +1310,7 @@ public:
 
     virtual TBasicType getBasicType() const { return basicType; }
     virtual const TSampler& getSampler() const { return sampler; }
+    virtual TSampler& getSampler() { return sampler; }
 
     virtual       TQualifier& getQualifier()       { return qualifier; }
     virtual const TQualifier& getQualifier() const { return qualifier; }