Minor edits to the config directory
Adds path compression to the rewrite function when rewriting to a FwdNode.
Adds macros BEGIN_EAGER and END_EAGER.  Cleans up the rfib, rfibn, and takn benchmarks.
Adds the need-ahead optimization for queens.

Running on gentoo.
------ Config gc-opt ------
queens               0:00.32
queensn              0:00.09
------ Config refcnt-opt ------
queens               0:00.53
queensn              0:00.20
------ Config ghc ------
queens               0:00.05
queensn              0:00.05