Fixed some technical problems with smart pointer support uncovered by

STLPort's debug mode. Unfortunately, had to expand Dereferenceable
requirements.


[SVN r16459]

libs/python

@@ -1 +1 @@
-Subproject commit bbef71dc7dd852e3a5cf70b0efc9319c943102bb
+Subproject commit 43a9571b2c9f7364e3bd644eb30b8d35f63cacbc