Rename add_to_list_top and add_to_list_bottom private methods to avoid_collision that handles both cases as well as the case where :add_new_at is nil. Setting an explicit position when :add_new_at is nil will now shuffle other items out of the way if necessary.
Rename
add_to_list_topandadd_to_list_bottomprivate methods toavoid_collisionthat handles both cases as well as the case where:add_new_atisnil. Setting an explicit position when:add_new_atisnilwill now shuffle other items out of the way if necessary.Fixes #410