Removed function SetModelTexture()

It's more educational to go through new material system, so, I decide to
remove this function to avoid students confusion...

examples/models_cubicmap.c

@@ -29,7 +29,7 @@ int main()
     
     // NOTE: By default each cube is mapped to one part of texture atlas
     Texture2D texture = LoadTexture("resources/cubicmap_atlas.png");    // Load map texture
-    SetModelTexture(&map, texture);                         // Bind texture to map model
+    map.material.texDiffuse = texture;                      // Set map diffuse texture
     
     Vector3 mapPosition = { -16.0f, 0.0f, -8.0f };          // Set model position
 

examples/models_heightmap.c

@@ -26,7 +26,7 @@ int main()
     Image image = LoadImage("resources/heightmap.png");         // Load heightmap image (RAM)
     Texture2D texture = LoadTextureFromImage(image);            // Convert image to texture (VRAM)
     Model map = LoadHeightmap(image, (Vector3){ 16, 8, 16 });   // Load heightmap model with defined size
-    SetModelTexture(&map, texture);                             // Bind texture to model
+    map.material.texDiffuse = texture;                          // Set map diffuse texture
     Vector3 mapPosition = { -8.0f, 0.0f, -8.0f };               // Set model position (depends on model scaling!)
 
     UnloadImage(image);                 // Unload heightmap image from RAM, already uploaded to VRAM

examples/models_obj_loading.c

@@ -25,7 +25,7 @@ int main()
 
     Model dwarf = LoadModel("resources/model/dwarf.obj");                   // Load OBJ model
     Texture2D texture = LoadTexture("resources/model/dwarf_diffuse.png");   // Load model texture
-    SetModelTexture(&dwarf, texture);                                       // Bind texture to model
+    dwarf.material.texDiffuse = texture;                                    // Set dwarf model diffuse texture
     Vector3 position = { 0.0f, 0.0f, 0.0f };                                // Set model position
 
     SetTargetFPS(60);   // Set our game to run at 60 frames-per-second

examples/shaders_custom_uniform.c

@@ -34,7 +34,7 @@ int main()
 
     Model dwarf = LoadModel("resources/model/dwarf.obj");                   // Load OBJ model
     Texture2D texture = LoadTexture("resources/model/dwarf_diffuse.png");   // Load model texture (diffuse map)
-    SetModelTexture(&dwarf, texture);                                       // Bind texture to model
+    dwarf.material.texDiffuse = texture;                                    // Set dwarf model diffuse texture
 
     Vector3 position = { 0.0f, 0.0f, 0.0f };                                // Set model position
     

examples/shaders_postprocessing.c

@@ -34,7 +34,7 @@ int main()
     
     Model dwarf = LoadModel("resources/model/dwarf.obj");                   // Load OBJ model
     Texture2D texture = LoadTexture("resources/model/dwarf_diffuse.png");   // Load model texture (diffuse map)
-    SetModelTexture(&dwarf, texture);                                       // Bind texture to model
+    dwarf.material.texDiffuse = texture;                                    // Set dwarf model diffuse texture
 
     Vector3 position = { 0.0f, 0.0f, 0.0f };                                // Set model position