Add the rummy family: meld engine + Gin, Rummy, Rummy 500, Hand & Foot

Introduce a shared meld engine and four games built on it, all on
cg-core/EIEIO with console UNICODE rendering.

* cg-rummy.el: the meld engine and Gin Rummy.  Set/run validation,
  candidate-meld enumeration, a bitmask-DP minimum-deadwood partition,
  and a layoff finder, plus the abstract cg-rummy-game base and shared
  render helpers.  Gin is two-handed with draw/take/discard/knock, gin
  and undercut bonuses, opponent layoffs, and play to 100.

* cg-rum500.el: the abstract cg-tablemeld-game (one mode and command
  set, dispatching on the subclass) driving Basic Rummy (meld out;
  score the cards left in other hands; to 100) and Rummy 500 (score the
  cards you lay down, lose those left in hand; ace high and worth 15;
  to 500).

* cg-handfoot.el: Hand & Foot, a partnership Canasta cousin.  Hand and
  foot packets, Twos and Jokers wild, rank books with clean/dirty piles,
  go-out bonus, and partnership scoring to 5000.  Deliberately

runemacs.sh

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+# Load the card-games package from this directory and open the launcher.
+dir="$(cd "$(dirname "$0")" && pwd)"
+exec emacs -L "$dir" -l card-games -f card-game "$@"