mkm3u: Use `-1' throughout as a sentinel title/chapter number.

[epls] / ultraviolet.epls

;;; -*-fundamental-*-

!vdir U/Ultraviolet
!explen 50:00

4       Habeas corpus
5       In nomine patris
6       Sub judice
9       Mea culpa
10      Terra incognita
11      Persona non grata