performance optimization.

The default user is the current user. If a different user's avatar is to be
shown, the user number must be passed on the command-line. Other command-line
options supported:
  -draw  = use the Graphic.draw() method to display anywhere (requires ANSI)
  -top   = display the avatar at the top of the screen
  -right = display the avatar at the right edge of the screen
  -above = display the avatar above the current cursor position

The -top/right/above options imply "draw", and all require ANSI support.
The default display method is to simply "show" the avatar (not draw) and that
does not require ANSI support, but can only display the avatar at the current
cursor location, left-justified.