Added support for DXT1/3/5 and BC5/7 compressed textures via love.image.CompressedData. Some internals are still iffy.

- added a new CompressedData type to love.image
- added love.image.isCompressed(file or data)
- love.graphics.newImage automatically tests for compression when loading a file
- added love.graphics.isSupported strings for DXT, BC5, and BC7

Compressed textures meant to be used on the GPU offer huge performance gains when
- loading the texture from a file
- loading the texture from RAM to VRAM
- loading mipmaps
- rendering

--HG--
branch : image-CompressedData

src/modules/image/devil/Image.h

@@ -24,6 +24,9 @@
 // LOVE
 #include "image/Image.h"
 
+// STL
+#include <string>
+
 namespace love
 {
 namespace image
@@ -46,6 +49,14 @@ public:
 	love::image::ImageData *newImageData(int width, int height);
 	love::image::ImageData *newImageData(int width, int height, void *data);
 
+	love::image::CompressedData *newCompressedData(love::filesystem::File *file);
+	love::image::CompressedData *newCompressedData(Data *data);
+
+	bool isCompressed(love::filesystem::File *file);
+	bool isCompressed(Data *data);
+
+	static const std::string compressedExts[];
+
 }; // Image
 
 } // devil