OpenGL 2.1 is now required to use love.graphics (resolves issue #779.)

Removed love.graphics.isSupported("canvas", "shader", "npot", "subtractive", and "mipmap"), since those features are all guaranteed by the minimum system requirements.

--HG--
branch : minor

src/modules/graphics/opengl/Image.h

@@ -127,14 +127,8 @@ public:
 	static void setDefaultMipmapFilter(FilterMode f);
 	static FilterMode getDefaultMipmapFilter();
 
-	static bool hasNpot();
 	static bool hasAnisotropicFilteringSupport();
-	static bool hasMipmapSupport();
-	static bool hasMipmapSharpnessSupport();
-
-	static bool hasCompressedTextureSupport();
 	static bool hasCompressedTextureSupport(image::CompressedData::Format format);
-
 	static bool hasSRGBSupport();
 
 private:
@@ -151,9 +145,6 @@ private:
 	// null if raw ImageData was used to create the texture.
 	love::image::CompressedData *cdata;
 
-	// Real dimensions of the texture, if it was auto-padded to POT size.
-	int paddedWidth, paddedHeight;
-
 	// OpenGL texture identifier.
 	GLuint texture;
 
@@ -175,7 +166,6 @@ private:
 
 	void preload();
 
-	void uploadTexturePadded();
 	void uploadTexture();
 
 	void uploadCompressedMipmaps();