Changing examples to use makefile

- Testing a modified version of the makefile from raylib Instead of multiple project files for examples.
- Fixed readme example

Examples/models/models_obj_loading.cs

@@ -0,0 +1,7 @@
+using Raylib;
+using static Raylib.Raylib;
+
+public partial class Examples
+{
+    /*******************************************************************************************
    *
    *   raylib [models] example - Load and draw a 3d model (OBJ)
    *
    *   This example has been created using raylib 1.3 (www.raylib.com)
    *   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
    *
    *   Copyright (c) 2014 Ramon Santamaria (@raysan5)
    *
    ********************************************************************************************/
    
    
    public static void Main()
    {
        // Initialization
        //--------------------------------------------------------------------------------------
        int screenWidth = 800;
        int screenHeight = 450;
    
        InitWindow(screenWidth, screenHeight, "raylib [models] example - obj model loading");
    
        // Define the camera to look into our 3d world
        Camera camera = { 0 };
        camera.position = new Vector3( 8.0f, 8.0f, 8.0f );;    // Camera position
        camera.target = new Vector3( 0.0f, 2.5f, 0.0f );;      // Camera looking at point
        camera.up = new Vector3( 0.0f, 1.0f, 0.0f );;          // Camera up vector (rotation towards target)
        camera.fovy = 45.0f;                                // Camera field-of-view Y
        camera.type = CAMERA_PERSPECTIVE;                   // Camera mode type
    
        Model model = LoadModel("resources/models/castle.obj");                 // Load OBJ model
        Texture2D texture = LoadTexture("resources/models/castle_diffuse.png"); // Load model texture
        model.material.maps[MAP_DIFFUSE].texture = texture;                     // Set map 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
        //--------------------------------------------------------------------------------------
    
        // Main game loop
        while (!WindowShouldClose())    // Detect window close button or ESC key
        {
            // Update
            //----------------------------------------------------------------------------------
            //...
            //----------------------------------------------------------------------------------
    
            // Draw
            //----------------------------------------------------------------------------------
            BeginDrawing();
    
                ClearBackground(RAYWHITE);
    
                BeginMode3D(camera);
    
                    DrawModel(model, position, 0.2f, WHITE);   // Draw 3d model with texture
    
                    DrawGrid(10, 1.0f);         // Draw a grid
    
                    DrawGizmo(position);        // Draw gizmo
    
                EndMode3D();
                
                DrawText("(c) Castle 3D model by Alberto Cano", screenWidth - 200, screenHeight - 20, 10, GRAY);
    
                DrawFPS(10, 10);
    
            EndDrawing();
            //----------------------------------------------------------------------------------
        }
    
        // De-Initialization
        //--------------------------------------------------------------------------------------
        UnloadTexture(texture);     // Unload texture
        UnloadModel(model);         // Unload model
    
        CloseWindow();              // Close window and OpenGL context
        //--------------------------------------------------------------------------------------
    
        return 0;
    }    
+}