Add rounding to sin/cos calc to improve accuracy

src/scripts/hrturtle.4th

@@ -9,7 +9,7 @@ SRC" TURTLE.4TH"
 : SHOW
   0 HGRMODE HGRDRAWBUF TILEDRAWBUF DROP
   280 192 INITTURTLE
-  1 HGRCOLOR
+  3 HGRCOLOR
 ;
 
 : SQUARE
@@ -20,7 +20,7 @@ SRC" TURTLE.4TH"
 ;
 
 : SPIN
-    360 0 DO
+    361 0 DO
         50 SQUARE
         I TURNTO
     10 +LOOP
@@ -30,3 +30,5 @@ SRC" TURTLE.4TH"
     SHOW
     SPIN
 ;
+
+SHOW SPIN