Add standing Sierpinsky Triangle demo

editor/standing-sierpinsky.c6l

@@ -0,0 +1,13 @@
+if first() then
+    clear_screen()
+end
+
+yh = 0
+for y do 200 times
+    x = bitand(time(), y)
+    xo = x - 100 - yh
+    pixel_draw(xo, y)
+    if bitand(y, 1) == 1 then
+        yh = yh + 1
+    end
+end