Implement automatic batching for points, lines, shapes, and images/quads.

The above are batched together into a single draw call when called without other drawing calls in between, as long as the following criteria are met:

- The texture is the same.
- The primitive type is the same (points cannot be batched with non-points).
- The love.graphics state is the same (aside from the current color - i.e. setColor - and the transform state).
- The active shader’s uniform values are the same.

You can examine the ‘drawcalls’ field of love.graphics.getStats() to help determine if your code is allowing for optimum batching.

--HG--
branch : minor

src/common/Matrix.cpp

@@ -97,7 +97,7 @@ Matrix4::~Matrix4()
 Matrix4 Matrix4::operator * (const Matrix4 &m) const
 {
 	Matrix4 t;
-	multiply(*this, m, t);
+	multiply(*this, m, t.e);
 	return t;
 }