Deleting AAs: Please test

[dsimcha]

Since conservative GC often interacts poorly with large AAs, I've been
requesting that AAs be deletable just like dynamic arrays and class objects.
Also, I've noticed that several people on this newsgroup in the past have
requested a clear function for AAs.  I've created a combination of a
delete/clear function and a patch for aaA.d that allow AAs to be used without
the GC without leaking memory if deleteAA() is called when the user is done
with the AA.  Please test and comment on this code so that we can finally have
the delete keyword for AAs, consistent with dynamic arrays.  The code is
available at:

http://d.puremagic.com/issues/show_bug.cgi?id=2105