Release 0.1.0 was obviously in 2020 and not in 2019.

Fixes: https://gitlab.gnome.org/BjoernDaase/journable/-/issues/4

Release 0.1 is actually release 0.1.0. Adjust the version accordingly.

The JournableWindow class needs to import Gtk. It means that the
require_version check needs to be before the window import.

Related: https://gitlab.gnome.org/BjoernDaase/journable/-/issues/3

This replaces TextViews with SourceViews and TextBuffers with
SourceBuffers which, among others, enables undo/redo functionality
in the journal cells.

Fixes: https://gitlab.gnome.org/BjoernDaase/journable/-/issues/3

This implements the new logic for dealing with multiple journals.
It works as follows:
1. The first time you close Journable you will be prompted to save
your journal
2. When you reopen Journable it will reopen the last open file
3. The Clear button clears the current journal
4. A New button was added to create a new empty journal (again, you have
to explicitly choose a file to save this to on close)

Fixes: https://gitlab.gnome.org/BjoernDaase/journable/-/issues/1

A Gtk.Bin is a Gtk.Container, so no need to distinguish here.
This also fixes a bug, that the header_bar would never be found in
find_child()

This adds a regular, development as well as the symbolic icon (and their
shared source svg).
While the regular and symbolic icon are used right away, the development
icon is not yet used (probably until we have nightly builds enabled).

Fixes: https://gitlab.gnome.org/BjoernDaase/journable/-/issues/2