Done (r3355-r3372).

All historical versions of the code that I still had floating around somewhere
are now available as old revisions of branches/ancient. Some highlights include
the "official IPC 2004 distribution" (r3369) and the last pre-repository version
that was still available (r3371). The branch has been deleted again in r3372.

These old versions should be put into the repository in some branch (maybe named
"ancient" or something like that). Suggested procedure:

  * Add 0.1 version, commit.
  * Replace with 0.2 version, commit.
  * ...
  * Replace with 1.0 version, commit.
  * Replace with "search-regular" version, commit. (If that makes sense --
compare 1.0 to search-regular first.)
  * Delete the branch.

There may be additional code versions living somewhere, e.g. the one used for
the ICAPS 2004 paper or the one used for IPC 2004. If these can be found, of
course they should be committed, in the right temporal order, too.

Should also add a README or some such to ancient that gives some idea about the
history and which versions were the significant ones.