go: port command loop, save/restore, tcell terminal, and the binary

- command.c in full: the command dispatcher with repeat counts, run
  prefixes, ctrl-run door-stop mode, fight-to-death targeting, and all
  wizard debug commands; search, help, identify, d_level/u_level, call,
  current
- main.c completed: Run()/playit() with the C double ROGUEOPTS parse;
  exit()-anywhere becomes a gameEnd panic recovered in Run
- save.c + state.c: gob SaveState snapshot with explicit pointer-to-
  index fixups for equipment, monster rooms, and chase targets (the
  rs_fix_thing role); save file deleted on restore as in C; SIGHUP/
  SIGTERM autosave hook
- wizard.c completed (create_obj, show_map), passages.c add_pass
- term/: tcell/v2 Terminal — the one third-party dependency — replacing
  curses and mdport's 900-line key decoder; shell escape via suspend
- cmd/rogue: flags -s/-d, SEED (wizard), ROGUEOPTS, ROGUE_WIZARD

Tests: full scripted sessions through Run (quit, descend stairs,
3200-move crash sweep, save-command round trip). Notable fixes found
by tests: gob silently drops embedded fields of unexported types, and
--More-- prompts swallow space-free input scripts.

game/rip.go

@@ -216,6 +216,26 @@ func (g *RogueGame) killname(monst byte, doart bool) string {
 	return sp
 }
 
+// DeathDemo implements the -d command line option (main.c): burn some
+// random numbers to break patterns, then die a random death.
+func (g *RogueGame) DeathDemo() {
+	defer func() {
+		if r := recover(); r != nil {
+			if _, ok := r.(gameEnd); ok {
+				return
+			}
+			panic(r)
+		}
+	}()
+	dnum := g.rnd(100)
+	for dnum--; dnum > 0; dnum-- {
+		g.rnd(100)
+	}
+	g.Player.Purse = g.rnd(100) + 1
+	g.Depth = g.rnd(100) + 1
+	g.death(g.deathMonst())
+}
+
 // deathMonst returns a monster appropriate for a random death (rip.c
 // death_monst).
 func (g *RogueGame) deathMonst() byte {