Upgrade dependencies

Do not allow empty `title:` header field

Win installer: correct path for new notes

This release corrects a regression introduced with v1.15.0:

Under Windows the context menu entry "New Tp-Note" did not
work because the path to the binary was not updated.

Rename binaries and installer packages to `tpnote`

This closes:

[shorter binary name · Issue #7 · getreu/tp-note](https://github.com/getreu/tp-note/issues/7)

New flag `--tty` to force console mode

when it is not detected automatically.
See manual page for details.

Minor bug fix: allow empty stem in file names

The bug fix in this release concerns the foreign file annotation feature
that raised a panic when annotating a file, whose filename contains en
empty file stem, e.g.: `306.pdf`. In this example, the number represents
the _sort tag_ of the filename, while `.pdf` is its file extension. The
file stem, the part in between, is the empty string.

This release parses those filenames correctly. It also completes the
migration to the `*.txt` file extension as default for Tp-Note (started
in v1.14.0): All functional tests are finally updated and should pass
again.

This release also fixes a minor conditional compilation issue introduced
with v1.14.0: some combination of optional features did not compile due
to missing imports.

Improve corner case error handling

Add more non-fatal error types

Tp-Note's default filename extension is now `.txt`

This change only concerns the creation of new notes. Existing notes with
ending `*.md` can be opened and edited as before.

If you prefer the previous behaviour, set the following in Tp-Note's
configuration file:

   [filename]
   extension_default = 'md'

   [viewer]
   missing_header_disables = false'

Improve error msg for --export

Win: add context menu entry "Export Tp-Note"

refactor build environment

add basic Wikitext support

print used config file path with `--version`

new config feature: delay the browser/editor start

fix a regression introduced with commit 9607745

First runs of newly installed Tp-Note binaries will create missing
directories in the configuration file path again. This regression was
introduced with commit 9607745.

This release also slightly changes the filename generation of new note
files by upgrading the dependency `sanitize-filename-reader-friendly` to
version 2.1.1. Now the Unicode character U+200b (non-printing space) is
also filtered when sanitizing filenames.

make sort-tag scheme configurable

Besides some dependency migration and refactoring
of the configuration file format, this release
allows to implement/configure your own sort-tag scheme
(cf. variables `[filename] sort_tag_chars` and
`[filename] sort_tag_extra_separator`.

group configuration file variables

allow keeping notes in a separate dir

default config: launch browser in private mode