Add functions for tracking GObject based items.

[David Hampton]

Log Message:
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Add functions for tracking GObject based items.  To help find memory
leaks, if gnucash is compiled with --enable-ref-counts-dumps the
contents of this database will be dumped when gnucash quits.

Tags:
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gnucash-gnome2-dev

Modified Files:
--------------
    gnucash:
        configure.in
    gnucash/src/core-utils:
        Makefile.am

Added Files:
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    gnucash/src/core-utils:
        gnc-gobject-utils.c
        gnc-gobject-utils.h