Add a new “stencil8” pixel format for Canvases (resolves issue #1003).

Also fixed Canvas MSAA (resolves issue #1271).

stencil-formatted Canvases can’t be drawn, and can only be used as the value for a new ‘depthstencil’ field to the table-argument variant of love.graphics.setCanvas.

--HG--
branch : minor

src/common/pixelformat.h

@@ -57,6 +57,9 @@ enum PixelFormat
 	PIXELFORMAT_RGB10A2,
 	PIXELFORMAT_RG11B10F,
 
+	// depth/stencil formats
+	PIXELFORMAT_STENCIL8,
+
 	// compressed formats
 	PIXELFORMAT_DXT1,
 	PIXELFORMAT_DXT3,
@@ -106,6 +109,11 @@ bool getConstant(const char *in, PixelFormat &out);
  **/
 bool isPixelFormatCompressed(PixelFormat format);
 
+/**
+ * Gets whether the specified pixel format is a depth/stencil type.
+ **/
+bool isPixelFormatDepthStencil(PixelFormat format);
+
 /**
  * Gets the size in bytes of the specified pixel format.
  * NOTE: Currently returns 0 for compressed formats.