Move shaders functions to module rlgl

Shader functionality owns to rlgl, not core module

src/rlgl.h

@@ -212,14 +212,11 @@ void rlglInitGraphics(int offsetX, int offsetY, int width, int height);  // Init
 unsigned int rlglLoadTexture(void *data, int width, int height, int textureFormat, int mipmapCount);       // Load in GPU OpenGL texture
 void rlglGenerateMipmaps(unsigned int textureId);                           // Generate mipmap data for selected texture
 
-Shader rlglLoadShader(char *vsFileName, char *fsFileName);                  // Load a shader (vertex shader + fragment shader) from files
-unsigned int rlglLoadShaderFromText(char *vShaderStr, char *fShaderStr);    // Load a shader from text data
+// NOTE: There is a set of shader related functions that are available to end user,
+// to avoid creating function wrappers through core module, they have been directly declared in raylib.h
+
 void rlglInitPostpro(void);                     // Initialize postprocessing system
 void rlglDrawPostpro(void);                     // Draw with postprocessing shader
-void rlglSetPostproShader(Shader shader);       // Set postprocessing shader
-void rlglSetModelShader(Model *model, Shader shader);   // Set shader for a model
-void rlglSetCustomShader(Shader shader);        // Set custom shader to be used on batch draw
-void rlglSetDefaultShader(void);                // Set default shader to be used on batch draw
 
 Model rlglLoadModel(VertexData mesh);           // Upload vertex data into GPU and provided VAO/VBO ids
 void rlglDrawModel(Model model, Vector3 position, float rotationAngle, Vector3 rotationAxis, Vector3 scale, Color color, bool wires);