Added the context() member functions, which returns a pointer to the native device context handle (an HDC on Windows, or a GC for X11).

Added the fillChord() and fillChords() member functions to class FXDC (and its subclasses) for drawing filled chord arcs. These augment the pie sector methods already present.

Renamed the getTextFont() and setTextFont() member functions to getFont() and setFont(), respectively.