Make a session sort of look like a QofEntity.

[Derek Atkins]

Log Message:
-----------
Make a session sort of look like a QofEntity.

	* src/engine/qofsession-p.h, src/engine/qofsession.c:
	  Make a session sort of look like a QofEntity.  This will
	  be useful when I add scheme bindings to the hooks.

Tags:
----
gnucash-gnome2-dev

Modified Files:
--------------
    gnucash:
        ChangeLog
    gnucash/src/engine:
        qofsession-p.h
        qofsession.c