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/weapons.go

@@ -36,7 +36,7 @@ func (g *RogueGame) doMotion(obj *Object, ydelta, xdelta int) {
 	obj.Pos = p.Pos
 	for {
 		// Erase the old one
-		if obj.Pos != p.Pos && g.cansee(obj.Pos.Y, obj.Pos.X) && !g.Options.Terse {
+		if obj.Pos != p.Pos && g.canSee(obj.Pos.Y, obj.Pos.X) && !g.Options.Terse {
 			ch := g.Level.Char(obj.Pos.Y, obj.Pos.X)
 			if ch == Floor && !g.showFloor() {
 				ch = ' '
@@ -51,7 +51,7 @@ func (g *RogueGame) doMotion(obj *Object, ydelta, xdelta int) {
 		ch := g.Level.VisibleChar(obj.Pos.Y, obj.Pos.X)
 		if stepOk(ch) && ch != Door {
 			// It hasn't hit anything yet, so display it if it's alright.
-			if g.cansee(obj.Pos.Y, obj.Pos.X) && !g.Options.Terse {
+			if g.canSee(obj.Pos.Y, obj.Pos.X) && !g.Options.Terse {
 				g.mvaddch(obj.Pos.Y, obj.Pos.X, obj.Kind.Glyph())
 				g.refresh()
 			}
@@ -70,7 +70,7 @@ func (g *RogueGame) fall(obj *Object, pr bool) {
 		pp.Ch = obj.Kind.Glyph()
 
 		obj.Pos = fpos
-		if g.cansee(fpos.Y, fpos.X) {
+		if g.canSee(fpos.Y, fpos.X) {
 			if pp.Monst != nil {
 				pp.Monst.OldCh = obj.Kind.Glyph()
 			} else {