don't draw blocks outside the playground area; spawn minos at y=-1

ttrs.py

@@ -173,6 +173,9 @@ class Playground():
             for y in range(self.height):
                 frame.setPixel(xpos + x, ypos + y, (0, 0, 0))
         for b in set.union(self.blocks, *[ m.blocks for m in self.minos ]):
+            if not self.contains_points([b.pos]):
+                # don't draw blocks outside the playground area
+                continue
             frame.setPixel(xpos + int(b.pos.x), ypos + int(b.pos.y), b.color)
 
 class TtrsPlayer():
@@ -248,7 +251,7 @@ class TtrsGame():
 
     def run(self):
         self.running = True
-        spawnpos = Point(self.playground.width // 2, 0)
+        spawnpos = Point(self.playground.width // 2, -1)
         mino = None
         TICK_TIME = 0.1
         FALL_INTERVAL = 5