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/Graphics.cpp

@@ -86,6 +86,11 @@ Graphics::~Graphics()
 		Shader::defaultShader->release();
 		Shader::defaultShader = nullptr;
 	}
+	if (Shader::defaultVideoShader)
+	{
+		Shader::defaultVideoShader->release();
+		Shader::defaultVideoShader = nullptr;
+	}
 
 	if (quadIndices)
 		delete quadIndices;
@@ -320,6 +325,13 @@ bool Graphics::setMode(int width, int height)
 		Shader::defaultShader = newShader(Shader::defaultCode[renderer]);
 	}
 
+	// and a default video shader.
+	if (!Shader::defaultVideoShader)
+	{
+		Renderer renderer = GLAD_ES_VERSION_2_0 ? RENDERER_OPENGLES : RENDERER_OPENGL;
+		Shader::defaultVideoShader = newShader(Shader::defaultVideoCode[renderer]);
+	}
+
 	// A shader should always be active, but the default shader shouldn't be
 	// returned by getShader(), so we don't do setShader(defaultShader).
 	if (!Shader::current)
@@ -819,6 +831,11 @@ Text *Graphics::newText(Font *font, const std::vector<Font::ColoredString> &text
 	return new Text(font, text);
 }
 
+Video *Graphics::newVideo(love::video::VideoStream *stream)
+{
+	return new Video(stream);
+}
+
 bool Graphics::isGammaCorrect() const
 {
 	return love::graphics::isGammaCorrect();