Added an implementation of Fibonacci heap.
Removed a bunch of deprecated stuff from utilities.
Added dlist.lisp, first attempt at making extract-min cons less.
Switched to using a inline version of dappend in fibheap.
Fixed bug in MEAN.
Removed format-to-string.
Made subtensor~ generic, lots of tweaks to infix. The copyright on infix has temporarily been removed to aid hackability. It will be put back on; Mark Kantrowicz still holds the copyright for the code he wrote.
Added clause for detecting empty slices.
Added a setf method for subtensor~. Infix now returns slicing list, when appropriate.