Restore three lost C behaviors: schtick message, forced redraw, greeting (closes #13)

Three behaviors from 5.4.4 that the port dropped silently. Each is a few
lines; grouped because they are all "restore something C did".

1. sticks.c 237: the "otherwise" arm closing do_zap's switch printed
   "what a bizarre schtick!", and doZap had turned it into doing nothing.
   The arm is under #ifdef MASTER, not under a runtime wizard test, so in
   the MASTER build this port is it printed for every player and must not
   be gated on g.Wizard. WS_NOP is a case of that switch in its own right
   ("when WS_NOP: break;"), so "no handler ran" cannot be the trigger:
   the wand of nothing does nothing quietly. C's switch covers all 14 WS_
   values, so its otherwise is reachable only for an o_which outside the
   table, which is what Object.hasValidWhich already screens for. All
   three arms fall through to obj.Charges--, as C's do.

2. command.c 288-291: CTRL('R') is "after = FALSE; clearok(curscr, TRUE);
   wrefresh(curscr);" — a forced full repaint. The port called
   g.refresh(), the ordinary diffing blit, which cannot fix the only
   situation the command exists for: a screen corrupted by another
   program's output leaves the game's record of it still correct, so the
   diff sends nothing. New Terminal.Repaint (tcell Screen.Sync, which
   discards tcell's record of the terminal rather than diffing against
   it), Screen.Repaint and g.repaint(), implemented in term.Tcell and in
   both headless test terminals. Named for the curses operation: the
   interface is the game's abstraction, not tcell's. It repaints what was
   last rendered — C repainted curscr, not stdscr — so it takes no
   window.

3. main.c 107-113: the startup greeting existed nowhere in the tree. New
   game.Greeting, printed on stdout by cmd/rogue/main.go before
   term.New(), the port's initscr(). Only the wizard wording is #ifdef
   MASTER; the other is unconditional. The %d is dnum, which main.c has
   just assigned to seed, so it is Params.Seed. Neither wording ends in a
   newline. Two placement details the tests pin: the printf sits after
   parse_opts, so a ROGUEOPTS name= is what the player is greeted by; and
   it sits after the -s/-d handling and after restore(), which never
   returns, so a resumed game does not announce that a dungeon is being
   dug (digsNewDungeon).

Greeting parses ROGUEOPTS into a throwaway game built the way New builds
the real one, tables and home directory included: ParseOpts handles every
option, not just the one the greeting reads, and inven= is matched
against inv_t_name[], which lives on the game.

All three message strings verified byte-for-byte against origin/c-master
sticks.c and main.c. No RNG call is added on any path and nothing under
game/testdata/ changed; TestSeedCompatItemTables is green against the
untouched golden.

Mutation-proved, each behavior removed in turn with only its own test
failing: dropping the message arm fails
TestZapUnhandledWandSaysBizarreSchtick; extending the message to WS_NOP
fails TestZapWandOfNothingIsSilent; putting g.refresh() back fails
TestRedrawCommandForcesFullRepaint; swapping the two wordings, and
ignoring the ROGUEOPTS name, both fail TestGreeting; greeting on the
restore path fails TestDigsNewDungeon.

ARCHITECTURE.md 5.3 gains Repaint and why a blit cannot substitute for
it; nothing here is deliberately dropped, so section 9 is unchanged.
TODO.md gets a Completed Steps entry; Next Step deliberately not rotated,
this being out-of-band issue work.

game/screen.go

@@ -23,6 +23,15 @@ type Terminal interface {
 	// the one Terminal method called from another goroutine, so an
 	// implementation must be safe to call concurrently with ReadChar.
 	Interrupt()
+	// Repaint forces the device to redraw every cell it is showing, the
+	// redraw command's whole point (curses clearok(curscr, TRUE) followed
+	// by wrefresh(curscr)). Render cannot stand in for it: a device that
+	// diffs against its own idea of what is on screen will do nothing at
+	// all when the screen has been corrupted by something else's output,
+	// which is the case the player types CTRL-R for. It repaints what was
+	// last rendered — C repainted curscr, not stdscr — so it neither
+	// needs nor takes a window.
+	Repaint()
 	// Fini restores the device to its pre-game state (curses endwin). The
 	// game calls it on its way out, since one game run is one process.
 	Fini()
@@ -223,6 +232,14 @@ func (s *Screen) Refresh() {
 	}
 }
 
+// Repaint forces the device to redraw everything it is showing, if there
+// is a device (curses clearok(curscr, TRUE) + wrefresh(curscr)).
+func (s *Screen) Repaint() {
+	if s.term != nil {
+		s.term.Repaint()
+	}
+}
+
 // Fini restores the terminal device, if there is one (curses endwin).
 func (s *Screen) Fini() {
 	if s.term != nil {
@@ -263,3 +280,4 @@ func (g *RogueGame) standend()                 { g.scr.Std.Standout(false) }
 func (g *RogueGame) clear()                    { g.scr.Std.Clear() }
 func (g *RogueGame) clrtoeol()                 { g.scr.Std.Clrtoeol() }
 func (g *RogueGame) refresh()                  { g.scr.Refresh() }
+func (g *RogueGame) repaint()                  { g.scr.Repaint() }