Rename combat methods; -1 status codes become named bool results

Refactor step 5, combat: rollEm→rollAttacks; attack, moveMonster, and
chaseStep return (removed bool) instead of the C -1/0 int codes.
Behavior unchanged; suite green.

game/chase.go

@@ -13,12 +13,12 @@ func (g *RogueGame) runners(int) {
 			origPos := tp.Pos
 
 			wastarget := tp.On(Targeted)
-			if g.moveMonster(tp) == -1 {
+			if removed := g.moveMonster(tp); removed {
 				continue
 			}
 
 			if tp.On(Flying) && distCp(g.Player.Pos, tp.Pos) >= 3 {
-				if g.moveMonster(tp) == -1 {
+				if removed := g.moveMonster(tp); removed {
 					continue
 				}
 			}
@@ -38,23 +38,24 @@ func (g *RogueGame) runners(int) {
 }
 
 // moveMonster executes a single turn of running for a monster (chase.c
-// move_monst). Returns -1 if the monster died or left the level.
-func (g *RogueGame) moveMonster(tp *Monster) int {
+// move_monst). removed reports that the monster died or left the level
+// (the C -1 return).
+func (g *RogueGame) moveMonster(tp *Monster) (removed bool) {
 	if !tp.On(Slowed) || tp.Turn {
-		if g.chaseStep(tp) == -1 {
-			return -1
+		if g.chaseStep(tp) {
+			return true
 		}
 	}
 
 	if tp.On(Hasted) {
-		if g.chaseStep(tp) == -1 {
-			return -1
+		if g.chaseStep(tp) {
+			return true
 		}
 	}
 
 	tp.Turn = !tp.Turn
 
-	return 0
+	return false
 }
 
 // relocate makes the monster's new location be the specified one, updating
@@ -86,9 +87,10 @@ func (g *RogueGame) relocate(th *Monster, newLoc Coord) {
 	}
 }
 
-// chaseStep makes one thing chase another (chase.c do_chase). Returns -1
-// if the chaser died in the attempt.
-func (g *RogueGame) chaseStep(th *Monster) int {
+// chaseStep makes one thing chase another (chase.c do_chase). removed
+// reports that the chaser died or left the level in the attempt (the C
+// -1 return).
+func (g *RogueGame) chaseStep(th *Monster) (removed bool) {
 	p := &g.Player
 	stoprun := false // true means we are there
 	mindist := 32767
@@ -153,7 +155,7 @@ func (g *RogueGame) chaseStep(th *Monster) int {
 					g.Kamikaze = false
 				}
 
-				return 0
+				return false
 			}
 		}
 
@@ -188,7 +190,7 @@ func (g *RogueGame) chaseStep(th *Monster) int {
 		}
 	} else {
 		if th.Type == 'F' {
-			return 0
+			return false
 		}
 	}
 
@@ -198,7 +200,7 @@ func (g *RogueGame) chaseStep(th *Monster) int {
 		th.Flags.Clear(Awake)
 	}
 
-	return 0
+	return false
 }
 
 // chase finds the spot for the chaser to move closer to the chasee