Rename item-subsystem methods (refactor step 5, items)

getItem→promptPackItem now returns (obj, ok) instead of a nil-signaling
pointer; invName→inventoryName; doPot→applyPotionFuse. C breadcrumbs
kept. Behavior unchanged; suite green.

game/wizard.go

@@ -119,7 +119,7 @@ func (g *RogueGame) whatis(insist bool, kind ObjectKind) {
 
 	var obj *Object
 	for {
-		obj = g.getItem("identify", kind)
+		obj, _ = g.promptPackItem("identify", kind)
 
 		if !insist {
 			break
@@ -161,7 +161,7 @@ func (g *RogueGame) whatis(insist bool, kind ObjectKind) {
 		setKnow(obj, g.Items.Rings[:])
 	}
 
-	g.msg("%s", g.invName(obj, false))
+	g.msg("%s", g.inventoryName(obj, false))
 }
 
 // setKnow sets things up when we really know what a thing is (wizard.c