Rename movement/world methods to idiomatic Go; remove all gotos

Refactor step 4. Renames (C breadcrumbs kept in doc comments):
doMove→moveHero, beTrapped→springTrap, rndmove→randomStep,
doRooms→digRooms, doPassages→digPassages, doMaze→digMaze,
chgStr→changeStrength, doRun→startRun, moveStuff→finishMove,
turnref→turnRefresh, moveMonst→moveMonster, doChase→chaseStep,
setOldch→setOldChar, cansee→canSee, roomin→roomIn, runto→runTo,
conn→connectRooms, putpass→putPassage, passnum→numberPassages,
numpass→numberPassage, rndPos→randomPos, rndRoom→randomRoom,
treasRoom→treasureRoom, accntMaze→accountMaze.

All goto/label flows are gone: moveHero uses a retry loop with the
PASSGO corner logic extracted into passageTurn; dispatch re-dispatches
via a loop; chaseStep re-checks via a loop; saveGame uses a labeled
prompt loop. Control flow and RNG call order are unchanged; suite
green.

game/save.go

@@ -449,99 +449,102 @@ func (g *RogueGame) applySnapshot(st *SaveState) {
 	g.scr.Std.SetContents(st.Screen)
 }
 
-// saveGame implements the "save game" command (save.c save_game). The C
-// goto over/gotfile flow becomes the useDefault flag.
+// saveGame implements the "save game" command (save.c save_game). The
+// labeled prompt loop and the useDefault flag stand in for the C
+// goto over/gotfile flow.
 func (g *RogueGame) saveGame() {
 	g.Msgs.Mpos = 0
 
-over:
-	useDefault := false
-
-	if g.FileName != "" {
-		var c byte
-
-		for {
-			g.msg("save file (%s)? ", g.FileName)
-			c = g.readchar()
-
-			g.Msgs.Mpos = 0
-			if c == Escape {
-				g.msg("")
-
-				return
-			}
-
-			if c == 'n' || c == 'N' || c == 'y' || c == 'Y' {
-				break
-			}
-
-			g.msg("please answer Y or N")
-		}
-
-		if c == 'y' || c == 'Y' {
-			g.addstr("Yes\n")
-			g.refresh()
-
-			useDefault = true
-		}
-	}
-
+prompt:
 	for {
-		var buf string
-		if useDefault {
-			buf = g.FileName
-			useDefault = false
-		} else {
-			g.Msgs.Mpos = 0
-			g.msg("file name: ")
+		useDefault := false
 
-			if g.getStr(&buf, g.scr.Std) == Quit {
-				g.msg("")
+		if g.FileName != "" {
+			var c byte
 
-				return
-			}
-
-			g.Msgs.Mpos = 0
-		}
-		// test to see if the file exists
-		_, statErr := os.Stat(buf)
-		if statErr == nil {
 			for {
-				g.msg("File exists.  Do you wish to overwrite it?")
-				g.Msgs.Mpos = 0
+				g.msg("save file (%s)? ", g.FileName)
+				c = g.readchar()
 
-				c := g.readchar()
+				g.Msgs.Mpos = 0
 				if c == Escape {
 					g.msg("")
 
 					return
 				}
 
-				if c == 'y' || c == 'Y' {
+				if c == 'n' || c == 'N' || c == 'y' || c == 'Y' {
 					break
 				}
 
-				if c == 'n' || c == 'N' {
-					goto over
-				}
-
-				g.msg("Please answer Y or N")
+				g.msg("please answer Y or N")
 			}
 
-			g.msg("file name: %s", buf)
-			_ = os.Remove(g.FileName) // best effort, as in C (md_unlink)
+			if c == 'y' || c == 'Y' {
+				g.addstr("Yes\n")
+				g.refresh()
+
+				useDefault = true
+			}
 		}
 
-		g.FileName = buf
+		for {
+			var buf string
+			if useDefault {
+				buf = g.FileName
+				useDefault = false
+			} else {
+				g.Msgs.Mpos = 0
+				g.msg("file name: ")
 
-		err := g.saveFile(g.FileName)
-		if err != nil {
-			g.msg("%s", err.Error())
+				if g.getStr(&buf, g.scr.Std) == Quit {
+					g.msg("")
 
-			continue
+					return
+				}
+
+				g.Msgs.Mpos = 0
+			}
+			// test to see if the file exists
+			_, statErr := os.Stat(buf)
+			if statErr == nil {
+				for {
+					g.msg("File exists.  Do you wish to overwrite it?")
+					g.Msgs.Mpos = 0
+
+					c := g.readchar()
+					if c == Escape {
+						g.msg("")
+
+						return
+					}
+
+					if c == 'y' || c == 'Y' {
+						break
+					}
+
+					if c == 'n' || c == 'N' {
+						continue prompt // the C goto over: start again
+					}
+
+					g.msg("Please answer Y or N")
+				}
+
+				g.msg("file name: %s", buf)
+				_ = os.Remove(g.FileName) // best effort, as in C (md_unlink)
+			}
+
+			g.FileName = buf
+
+			err := g.saveFile(g.FileName)
+			if err != nil {
+				g.msg("%s", err.Error())
+
+				continue
+			}
+
+			break prompt
 		}
-
-		break
 	}
 
 	g.myExit()