LibDraw: Put all classes in the Gfx namespace

I started adding things to a Draw namespace, but it somehow felt really
wrong seeing Draw::Rect and Draw::Bitmap, etc. So instead, let's rename
the library to LibGfx. :^)

Libraries/LibDraw/CharacterBitmap.cpp

@@ -26,6 +26,8 @@
 
 #include "CharacterBitmap.h"
 
+namespace Gfx {
+
 CharacterBitmap::CharacterBitmap(const char* ascii_data, unsigned width, unsigned height)
     : m_bits(ascii_data)
     , m_size(width, height)
@@ -40,3 +42,5 @@ NonnullRefPtr<CharacterBitmap> CharacterBitmap::create_from_ascii(const char* as
 {
     return adopt(*new CharacterBitmap(asciiData, width, height));
 }
+
+}