Give item categories and subtypes real types (refactor step 2)

ObjectKind separates what an item is from how it draws: Object.Type
(a byte that doubled as the map character) becomes Kind ObjectKind,
with Glyph() producing the display character and objectKindForGlyph
converting back at the map boundary. KindWand covers the C 'stick'
category. The magic-missile bolt uses KindGold, matching C's literal
o_type='*' trick, with a comment.

PotionKind, ScrollKind, RingKind, WandKind, WeaponKind, ArmorKind and
TrapKind are now iota enums with Stringer (names come from the base
info tables); Object gains typed accessors (obj.RingKind(), ...) and
Launch is typed WeaponKind. beTrapped returns TrapKind. The
getItem/inventory/whatis prompt filters take ObjectKind, with
KindCallable/KindRingOrStick replacing the C CALLABLE/R_OR_S
sentinels; wizard.c's type_name table is subsumed by
ObjectKind.String(). IsRing/IsWearing/initWeapon/doPot signatures are
typed accordingly.

The save format version becomes 5.4.4-go2: the gob field rename would
otherwise silently zero Kind when reading old saves.

No behavior change; full suite green.

game/rip.go

@@ -115,37 +115,37 @@ func (g *RogueGame) totalWinner() {
 	for _, obj := range p.Pack {
 		worth := 0
 		it := &g.Items
-		switch obj.Type {
-		case Food:
+		switch obj.Kind {
+		case KindFood:
 			worth = 2 * obj.Count
-		case Weapon:
+		case KindWeapon:
 			worth = it.Weapons[obj.Which].Worth
 			worth *= 3*(obj.HPlus+obj.DPlus) + obj.Count
 			obj.Flags.Set(Known)
-		case Armor:
+		case KindArmor:
 			worth = it.Armors[obj.Which].Worth
 			worth += (9 - obj.Arm) * 100
 			worth += 10 * (aClass[obj.Which] - obj.Arm)
 			obj.Flags.Set(Known)
-		case Scroll:
+		case KindScroll:
 			op := &it.Scrolls[obj.Which]
 			worth = op.Worth * obj.Count
 			if !op.Know {
 				worth /= 2
 			}
 			op.Know = true
-		case Potion:
+		case KindPotion:
 			op := &it.Potions[obj.Which]
 			worth = op.Worth * obj.Count
 			if !op.Know {
 				worth /= 2
 			}
 			op.Know = true
-		case Ring:
+		case KindRing:
 			op := &it.Rings[obj.Which]
 			worth = op.Worth
-			if obj.Which == RingAddStrength || obj.Which == RingIncreaseDamage ||
-				obj.Which == RingProtection || obj.Which == RingDexterity {
+			if obj.RingKind() == RingAddStrength || obj.RingKind() == RingIncreaseDamage ||
+				obj.RingKind() == RingProtection || obj.RingKind() == RingDexterity {
 				if obj.Arm > 0 {
 					worth += obj.Arm * 100
 				} else {
@@ -157,7 +157,7 @@ func (g *RogueGame) totalWinner() {
 			}
 			obj.Flags.Set(Known)
 			op.Know = true
-		case Stick:
+		case KindWand:
 			op := &it.Sticks[obj.Which]
 			worth = op.Worth
 			worth += 20 * obj.Charges()
@@ -166,7 +166,7 @@ func (g *RogueGame) totalWinner() {
 			}
 			obj.Flags.Set(Known)
 			op.Know = true
-		case Amulet:
+		case KindAmulet:
 			worth = 1000
 		}
 		if worth < 0 {