The Key_List class has several strings that are initialized with static
strings.  In the Key_List::output_types () method their contents are changed to
strings that were allocated on the heap.  Deallocation of these strings never
occurs, nor can it occur if the members contain static strings.

Suggested Solution:  Remove the evil statically vs. dynamically allocated
strings assignments, and stick with one type of allocation (most likely
dynamically allocated strings).