* Add support for include_tasks. Fixes#13
* Use keyword arguments for _include_tasks_in_blocks
* Pass correct variable manager to load_list_of_blocks
* Option fail_on_undefined during template
* Rewrite test_grapher_simple_playbook
* add id to the root node, prefix for play and task ids
* make post_process_svg return output_filename
* Tests using Pyquery which use more user friendly