pkg: drop python 2.5 compatibility (closes #2711624)
2.5 is not common anymore. Dropping compatibility will help moving to a code
base compatible with Python 3.3
Data as objects
===============
In this chapter, we will introduce the objects that are used to handle
the logic associated to the data stored in the database.
.. toctree::
:maxdepth: 1
data-as-objects
load-sort
adapters
application-logic