Type.h: Add int16/uint16 typedefs
CompositeTexture: Update class description
CompositeTexture: Use temps, not repeated ops
Decode: Update logging in DecodeImageFile
test/compositetexture: Change fill color for visibility
Decode: Add sanity NULL-checking in debug config
CompositeTexture: Store corner dimensions, add getter
GlyphMap: Fix compiler warnings
test/font: 2D view span matches viewport size
Stamp: Documentation added
BezierCurve: Turn off verbose logging
Add Element class, base class for GUI elements
gdk/engine/Element: Frame, Anchor, Texture as member variables

These data won't freed or allocated directly by the Element. That is done
through the GUI class
Hoverable: Now accepts pointer coords
Hoverable: Add OnHover callback
gdk/engine/Element: Inherit Hoverable
gdk/engine/Element: Fix incorrect Texture pointer var
gdk/engine/Element: Trivial constructor
gdk/engine/GUI: Add class description
gdk/engine/GUI: Inherit Drawable