Role propagation & bug fixes (#87) * test * first version of trees * json read and write test * json read and write test * from_json classmethods * Simple UI implementation for trees * small typing changes * node tests * fixed node tests * changed collection to hold all json files, added a whole buncha TODOS * node tests and tree * example json files * updated tree * updated tests * documentation * collection works * comments for collection * comments for collection * Small fixes * Simple implementation of tree alignment * trying different method for tree positioning algorithm * Proper tree positioning algorithm * proper node alignment * refcctoring and comments * Finished tree structure alignment * Add zooming capabilities * cleanup * Added comments * Fixed node swapping * Lots of bug fixes, update_tree now supported * Delete __init__.py Fixes tests * update tree when deleting subtree * Correct node removal when canceling drag-drop