Added stack type enums to love.graphics.push (resolves issue #906.) Current enums are "transform" and "all". "transform" is the default (for compatibility.) When love.graphics.push("all") is used, love.graphics.pop() will restore all love.graphics module state to what it was when push was called.

Updated the graphics code to use a custom matrix stack rather than OpenGL1's APIs.

src/common/Matrix.h

@@ -150,6 +150,12 @@ public:
 	 **/
 	void transform(Vertex *dst, const Vertex *src, int size) const;
 
+	/**
+	 * Creates a new orthographic projection matrix with depth in the range of
+	 * [-1, 1].
+	 **/
+	static Matrix ortho(float left, float right, float bottom, float top);
+
 private:
 
 	/**