Added yet another allocator, and a simulator variant that uses it: a

simple free list using a mix of exact-fit and last-fit with a roving
pointer as suggested by Tim.  Use -f to use this version.

Renamed BuddyNode to BlockNode since it is now used by both allocators.

Moved some code around in an attempt to organize it more top-down.

Moved the report printing into the Simulation base class.  Print the
class name and exact cache size before the header; skip the final
report printing if only one previous report was printed.