Added lighting engine module

- New lighting engine module which contains new data types Light and
Material. These data types and functions facilitates making a basic 3D
iluminated program with a light and a model.

- Added lighting engine module example (currently included in raylib.h;
it might be compiled by separate and include lighting.h in game source C
file).

- Corrected some opengl defines control structures and added some TODO
to fix raylib-opengl 1.1 source build (note: now source can be compiled
without errors, but rlglReadPixels() won't work properly).

Note: most of functions of phong version 330 shader are not in v100
shaders, so I couldn't write a version 100 phong shader. These functions
are included from version 150.

src/lighting.h

@@ -0,0 +1,87 @@
+/*******************************************************************************************
+*
+*   raylib lighting engine module - Lighting and materials management functions
+*
+*   Copyright (c) 2015 Victor Fisac and Ramon Santamaria
+*
+*   This software is provided "as-is", without any express or implied warranty. In no event
+*   will the authors be held liable for any damages arising from the use of this software.
+*
+*   Permission is granted to anyone to use this software for any purpose, including commercial
+*   applications, and to alter it and redistribute it freely, subject to the following restrictions:
+*
+*     1. The origin of this software must not be misrepresented; you must not claim that you
+*     wrote the original software. If you use this software in a product, an acknowledgment
+*     in the product documentation would be appreciated but is not required.
+*
+*     2. Altered source versions must be plainly marked as such, and must not be misrepresented
+*     as being the original software.
+*
+*     3. This notice may not be removed or altered from any source distribution.
+*
+**********************************************************************************************/
+
+#ifndef LIGHTING_H
+#define LIGHTING_H
+
+//----------------------------------------------------------------------------------
+// Defines and Macros
+//----------------------------------------------------------------------------------
+//...
+
+//----------------------------------------------------------------------------------
+// Types and Structures Definition
+// NOTE: Below types are required for LIGHTING_STANDALONE usage
+//----------------------------------------------------------------------------------
+// Vector3 type
+typedef struct Vector3 {
+    float x;
+    float y;
+    float z;
+} Vector3;
+
+// Light type
+typedef struct Light {
+    float position[3];
+    float rotation[3];
+    float intensity[1];
+    float ambientColor[3];
+    float diffuseColor[3];
+    float specularColor[3];
+    float specularIntensity[1];
+} Light;
+
+// Material type
+typedef struct Material {
+    float ambientColor[3];
+    float diffuseColor[3];
+    float specularColor[3];
+    float glossiness[1];
+    float normalDepth[1];
+} Material;
+
+//----------------------------------------------------------------------------------
+// Module Functions Declaration 
+// NOTE: light and material structs uses float pointers instead of vectors to be compatible with SetShaderValue()
+//----------------------------------------------------------------------------------
+// Lights functions
+void SetLightPosition(Light *light, Vector3 position);                  // Set light position converting position vector to float pointer
+void SetLightRotation(Light *light, Vector3 rotation);                  // Set light rotation converting rotation vector to float pointer
+void SetLightIntensity(Light *light, float intensity);                  // Set light intensity value 
+void SetLightAmbientColor(Light *light, Vector3 color);                 // Set light ambient color value (it will be multiplied by material ambient color)
+void SetLightDiffuseColor(Light *light, Vector3 color);                 // Set light diffuse color (light color)
+void SetLightSpecularColor(Light *light, Vector3 color);                // Set light specular color (it will be multiplied by material specular color)
+void SetLightSpecIntensity(Light *light, float specIntensity);          // Set light specular intensity (specular color scalar multiplier)
+
+// Materials functions
+void SetMaterialAmbientColor(Material *material, Vector3 color);        // Set material ambient color value (it will be multiplied by light ambient color)
+void SetMaterialDiffuseColor(Material *material, Vector3 color);        // Set material diffuse color (material color, should use DrawModel() tint parameter)
+void SetMaterialSpecularColor(Material *material, Vector3 color);       // Set material specular color (it will be multiplied by light specular color)
+void SetMaterialGlossiness(Material *material, float glossiness);       // Set material glossiness value (recommended values: 0 - 100)
+void SetMaterialNormalDepth(Material *material, float depth);           // Set normal map depth (B component from RGB type map scalar multiplier)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // LIGHTING_H