Life: Disable draw button until setup is pressed

The model would throw an error otherwise when the instruction note on
the screen makes it seem like you should be able to draw right away.

Author: LaCuneta

Sample Models/Computer Science/Cellular Automata/Life.nlogox

@@ -82,7 +82,7 @@ you can add or remove
 cells by holding down
 the mouse button
 and "drawing".</note>
-    <button x="9" y="138" height="35" disableUntilTicks="false" forever="true" kind="Observer" width="103">draw-cells</button>
+    <button x="9" y="138" height="35" disableUntilTicks="true" forever="true" kind="Observer" width="103">draw-cells</button>
     <input x="119" multiline="false" y="328" height="60" variable="fgcolor" type="color" width="155">123.0</input>
     <input x="119" multiline="false" y="390" height="60" variable="bgcolor" type="color" width="155">79.0</input>
     <button x="11" y="221" height="38" disableUntilTicks="true" forever="false" kind="Observer" width="103" display="go-once">go</button>