A simple portrayal for 2D visualization of hexagons. It extends the SimplePortrayal2D and
it manages the drawing and hit-testing for hexagonal shapes. If the DrawInfo2D parameter
received by draw and hitObject functions is an instance of HexaDrawInfo2D, better information
is extracted and used to make everthing look better. Otherwise, hexagons may be created from
information stored in simple DrawInfo2D objects, but overlapping or extra empty spaces may be
observed (especially when increasing the scale).