qd-fun.lisp:
o Move implementations and timing/test functions to other file.

qd-extra.lisp:
o Stuff here.

qd.system:
o Add new system for the extra stuff.

quad-double.

qd-dd.lisp:
o Needed routines (taken from CMUCL)

qd.system:
o Compile qd-dd.lisp if needed.

qd-package.lisp:
o If on CMUCL, import the needed routines from the C package.

qd.lisp:
o Remove the C:: package qualifiers from the core double-double
  routines.

a portable presentation using a (simple-array double-float (4)) to
hold a %quad-double number.

All of the tests pass with the portable representation.

qd.lisp:
o Moved representation to qd-rep.lisp.
o INTEGER-DECODE-QD was dependent on the internal representation.
  Replace with a function using the appropriate accessors.

qd.system:
o Add new file qd-rep.lisp.

qd-rep.lisp:
o Representation moved here.
o Add portable implementation using a simple-array for holding a
  %quad-double.

x86.  For some reason, the result is very slow, and cons far more than
on ppc or sparc.

qd-io.lisp:
o New file

qd.lisp:
o Moved IO functions from here to qd-io.lisp.

qd.system:
o Added qd-io.lisp to defsystem.

if desired.

o Make sure qd-fun depends on qd-const.

o Add function to compute atan via Cordic
o Rename TAN-QD to CORDIC-TAN-QD
o Add TAN-QD that computes tan via sin/cos.