Log Message:
Update to 1.18a released by Marti Maria.  Call it 1.18.0.1 in pkgsrc
so that it sorts correctly, and leave 1.18.1 available for a possible
future upstream bugfix point release.

Changes since 1.18:

  incorporate the fix in our patch-aa

(No need to pull to pkgsrc-stable; this is the same as 1.18nb2)