tecat.tes and repl.tes are now executable scripts, even though they are
installed into the $SCITECOPATH.

This is still much slower than the Lua version here:
https://gist.github.com/rhaberkorn/6534ecf1b05de6216d0a9c33f31ab5f8

* Unfortunately, this will currently just terminate when some command fails.
  We require an error catching mechanism to fix this up.

Also use binary packages when testing with Poudriere
(gmake -f ./distribute.mk poudriere).

Especially useful since Gtk users are supposed to edit ~/.teco_css.

* Unfortunately, the Lexilla lexer does not recognize PostgreSQL multiline
  strings between $$...$$.
* All of the other SQL variants, that Scite supports, are skipped for the time
  being. They'd probably have to be separate SciTECO lexer configs anyway.

The email, git and sciteco lexer configurations are bundled even
without the LEXILLA option.

* After installation, SciTECO will therefore start into a more userfriendly mode
  even if the user does not create a custom ~/.teco_ini.
  It is hoped that this will scare away less of new users, who
  are not willing to read through all of the documentation.
  Still, users are warned in the absence of ~/.teco_ini.
  This warning however, might not be immediately visible, especially
  not when running gsciteco without an attached console.
  (This will change once I redo the UI and allow a number of messages
  to be queued in the message area.)
* Theoretically, you could also just extend fallback.teco_ini from ~/.teco_ini,
  but that would require installing it into $SCITECOPATH.
* Since the fallback profile will now be munged automatically
  on a wide range of systems, we set up xclip only when detecting X11
  ($DISPLAY is non-empty).
  E.g. when running under Wayland or the Linux console, you still won't
  get the clipboard registers, which is probably better than having the
  clipboard operations fail once you try to use them.
* xclip is now "suggested" on Debian/Ubuntu.
  Unfortunately we cannot pull it in only in the presence of X11.