_Parcheesi_

Parcheesi is a race game for four players. The goal is for
each player to move their pieces from the starting position
(the circles in the corners) to the home square (in the
center of the board), passing a nearly complete loop around
the board in the counter-clockwise direction and then heads
up towards the main row. For example, the green player
enters from the bottom right, travels around the board on
the light blue squares, passing each of the corners, until
it reaches the middle of the bottom of the board, where it
turns off the light blue squares and heads into the central
region.

On each turn, the player rolls two dice and advances the
pawn, based on the die rolls. Typically the players may move
a pawn for each die. The pawn moves by the number of pips
showing on the die and all of the dice must be used to
complete a turn.

There are some exceptions, however:

  - you must roll a 5 (either directly or via summing) to
    enter from the start area to the main ring.

  - if two pieces of the same color occupy a square, no
    pieces may pass that square.

  - if an opponent's piece lands on your piece, you piece is
    returned to the starting area and the opponent receives
    a bonus of 20 (which is treated just as if they had
    rolled a 20 on the dice)

  - if your piece makes it home (and it must do so by exact
    count) you get a bonus of 10, to be used as an
    additional die roll.

These rules induce a number of unexpected corner cases, but
the GUI only lets you make legal moves. Watch the space
along the bottom of the board for reasons why a move is
illegal or why you have not used all of your die rolls.

The automated players are:

 - Reckless Renee, who she tries to maximize the chances
   that someone else bops her.

 - Polite Polly, who tries to minimize the distance her
   pawns move ("no, after _you_. I insist."), and

 - Amazing Grace, who tries to minimize the chance she gets
   bopped while moving as far as possible.
