Add initial video playback support for Ogg Theora videos (resolves issue #66.)

The basic APIs are:

video = love.graphics.newVideo("myvideo.ogv")

love.graphics.draw(video, ...) -- Video objects are Drawables.

video:play(), video:pause()

video:getDuration(), video:tell(), video:rewind(), video:seek(seconds)

video:getSource()

video:getWidth(), video:getHeight(), video:setFilter(min, mag)

More advanced APIs include video:setSource(source), video:getStream(), and videostream:setSync.

To use a custom pixel shader when drawing a Video, call the new TexelVideo(texcoords) function instead of Texel(texture, texcoords) in order to get the pixel colors of a video frame.

src/modules/graphics/opengl/Shader.h

@@ -64,6 +64,9 @@ public:
 		BUILTIN_NORMAL_MATRIX,
 		BUILTIN_POINT_SIZE,
 		BUILTIN_SCREEN_SIZE,
+		BUILTIN_VIDEO_Y_CHANNEL,
+		BUILTIN_VIDEO_CB_CHANNEL,
+		BUILTIN_VIDEO_CR_CHANNEL,
 		BUILTIN_MAX_ENUM
 	};
 
@@ -89,9 +92,11 @@ public:
 
 	// Pointer to the default Shader.
 	static Shader *defaultShader;
+	static Shader *defaultVideoShader;
 
 	// Default shader code (a shader is always required internally.)
 	static ShaderSource defaultCode[Graphics::RENDERER_MAX_ENUM];
+	static ShaderSource defaultVideoCode[Graphics::RENDERER_MAX_ENUM];
 
 	/**
 	 * Creates a new Shader using a list of source codes.
@@ -182,6 +187,7 @@ public:
 	 **/
 	bool hasVertexAttrib(VertexAttribID attrib) const;
 
+	void setVideoTextures(GLuint ytexture, GLuint cbtexture, GLuint crtexture);
 	void checkSetScreenParams();
 	void checkSetPointSize(float size);
 	void checkSetBuiltinUniforms();
@@ -263,6 +269,8 @@ private:
 	Matrix4 lastTransformMatrix;
 	Matrix4 lastProjectionMatrix;
 
+	GLuint videoTextureUnits[3];
+
 	// Counts total number of textures bound to each texture unit in all shaders
 	static std::vector<int> textureCounters;