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/ImageData.cpp

@@ -39,14 +39,19 @@ ImageData::~ImageData()
 	delete mutex;
 }
 
+int ImageData::getSize() const
+{
+	return getWidth()*getHeight()*sizeof(pixel);
+}
+
 void *ImageData::getData() const
 {
 	return data;
 }
 
-int ImageData::getSize() const
+bool ImageData::inside(int x, int y) const
 {
-	return getWidth()*getHeight()*sizeof(pixel);
+	return x >= 0 && x < getWidth() && y >= 0 && y < getHeight();
 }
 
 int ImageData::getWidth() const
@@ -59,11 +64,6 @@ int ImageData::getHeight() const
 	return height;
 }
 
-bool ImageData::inside(int x, int y) const
-{
-	return x >= 0 && x < getWidth() && y >= 0 && y < getHeight();
-}
-
 void ImageData::setPixel(int x, int y, pixel c)
 {
 	if (!inside(x, y))