Version 0.6 (2009-02-08)
 - Read and write from Lisp streams, also those without file descriptors
 - Added unit tests.
 - Fixed pointer size bug causing memory fault on SBCL Linux x86_64.
 - Read, write, and represent 16-bit images.  (Previously downscaled
   to 8 bits on read.)
 - Fixed reading of 1, 2, and 4-bit images on CCL DarwinPPC.
Version 0.5 (2008-12-01)
 - Complete rewrite, using foreign calls to libpng.
Version 0.4 (2004-03-06)
 - Fix simple bug (#4) in package definition that made CL-PNG unloadable.
 - Fix simple bug (#5) that made memory allocation in UNCOMPRESS-STRING
   slightly inefficient.
 - Fix bug (#6) that made CL-PNG not work at all on CMUCL.
Version 0.3 (2004-03-05)
 - Use compression and decompression code from libz (via UFFI) instead
   of the CL implementation.
 - Changes (mostly cosmetic) from Kevin Rosenberg's Debian package.