tappet.in: Add the copyright.
tappet.in (export-log!): Export logs to HTML

* Makefile.am (Makefile.am): Add `dsv.scm'.
* dsv.scm: Add to the repository.
* tappet.in: Use it.
  (export-log!): Export logs to HTML.
  (export-month!): Make links to HTML logs.