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/math.h

@@ -72,13 +72,6 @@ struct Rect
 	}
 };
 
-struct Vertex
-{
-	float x, y;
-	float s, t;
-	unsigned char r, g, b, a;
-};
-
 inline int nextP2(int x)
 {
 	x += (x == 0);