Log Message:
dte: Update to 1.9.1

v1.9.1 (latest release)
-----------------------

**Changes:**

* Fixed `make check` when running from a release tarball.

v1.9
----

**Additions:**

* Added a new `pipe-to` command, to complement the existing `pipe-from`
  and `filter` commands.
* Added a new `show` command, which can be used to introspect the
  current values of aliases and bindings.
* Added a `-k` flag to the `copy` command, to allow keeping the current
  selection after copying.
* Added a man page entry for the (previously undocumented) `eval`
  command.
* Added new `$FILETYPE` and `$LINENO` special variables.
* Added a `display-invisible` global option, to allow visible rendering
  of otherwise invisible Unicode characters.
* Added an `-s` command-line flag, for validating custom syntax files.
* Added a compile-time `ICONV_DISABLE=1` option, which disables linking
  to the system iconv library (but makes the editor UTF-8 only).
* Added a Desktop Entry file, which can be installed using
  `make install-desktop-file`.

**Improvements:**

* Updated Unicode support to version 12.1.
* Modified the `errorfmt` command, to allow sub-match groups in the
  regexp pattern to be ignored.
* Various improvements to syntax highlighting and filetype detection.
* Various performance optimizations.

**Fixes:**

* Fixed a bug that would sometimes cause files to be saved as UTF-8,
  even if another encoding was specified.