add exceptions to the road map. i think this just was an oversight.

also a way to run code when object is deleted.
both of these are possibilities, not certainties.

R=rsc, iant
CC=golang-dev
https://golang.org/cl/181057

doc/devel/roadmap.html

@@ -32,7 +32,12 @@ Possibly rewrite restriction on goto across variable declarations.
 Variant types.  A way to define a type as being the union of some set
 of types.
 <li>
+Possibly provide a method that will be run by the garbage
+collector when an item is freed.
+<li>
 Generics.  An active topic of discussion.
+<li>
+Exceptions.  An active topic of discussion.
 </ul>
 
 <h3 id="Implementation_roadmap">