ExceptionHandler enhancement implemented in the exceptionmagic branch

[Allison Randal]

Stephen Weeks wrote:
> The exceptionmagic branch now holds an implementation of filtering
> exceptions in ExceptionHandler's can_handle.  If I could get some API
> feedback, that would be great.
> 
> Relevant commits are:
> http://www.parrotvm.org/svn/parrot/revision?rev=31331
> http://www.parrotvm.org/svn/parrot/revision?rev=31332
> http://www.parrotvm.org/svn/parrot/revision?rev=31355

Looks great, thanks! I especially appreciate the touch of making the 
'handle_types' method slurpy.

Allison