Patch by Christoph Holtermann:
For the more complex financial objects i chose a different approach.
The printing functions are located in one module. Importing this module adds
these functions as methods to the classes defined in gnucash_core.py.
git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@20145 57a11ea4-9604-0410-9ed3-97b8803252fd
