distro: Add the `guile', `typesetting', and `databases' package modules.

distro: Add the `guile', `typesetting', and `databases' package modules.

* distro.scm (package-files): Adjust PREFIX-LEN to use the top-level
  directory, not %DISTRO-MODULE-DIRECTORY.
* distro/packages/base.scm (guile-reader, guile-reader/guile-1.8,
  guile-reader/guile-2.0, lout, recutils): Move to...
* distro/packages/guile.scm, distro/packages/typesetting.scm,
  distro/packages/databases.scm: ... here.  New files.
* Makefile.am (MODULES): Add them.
  (EXTRA_DIST): Add `.dir-locals.el'.

* .dir-locals.el: New file, with settings formerly in `base.scm'.