Quasi renaming
renaming
renaming components for Bacon2D, also simplified them.  For example:
 QuasiGame -> Game
 QuasiEntity -> Entity
 QuasiImageLayer -> ImageLayer
 ..

The one exception was QuasiRectangle, I renamed Box to prevent
clashing with QtQuick's Rectangle.  The underlying class is still
Rectangle, but it's exposed as Box.  We can rename the class later
if desired.