Major Updates in oTree from versio 2 to 5:

1) The method before_next_subsession() has been replaced with creating_session(). This, however, executes for all rounds when the session is created; rather than before each round. Values should not be initialized for groups, players, etc. through calling methods in other classes in creating_session().

2) The method vars_for_all_templates() no longer functions. Instead, send the templates through each page's vars_for_template(). It is possible to create a method, shared_vars() is pages.py which returns a dictionary and add those values to each vars_for_template() via unpacking (e.g **shared_vars(self)).

3) Django is no longer being run in oTree Lite. This affects many template properties. For instance, player.method.element is no longer supported. Instead, pass the method as a var for the template in pages.py.

There are plenty of other minor compatibility issues that may be dealt with as well.

4) Miscelleaneous errors in the code were corrected.