Check whether nodes exist before accessing their filters
Add set files for set configuration
Add set configuration
Use set_cfg in ll_test
Merge pull request #122 from neithernut/add-tests-set_cfg

Add tests set cfg
Merge pull request #119 from neithernut/fix-avl-regen_metadata

Fix crashes in regen_metadata
Add internal function for recursive removal of an element
Adjust declaration of avl_del
Add implementation of avl_del