Patch release to fix a bug when using the Flatpak package.

Fixed:

• Fixed a Flatpak bug where the app couldn't call binaries on the host, such as `git`, `svn`, etc.

With this release, the main end-user change is the new icon. The rest is mainly maintenance improvements with a much more standard folder structure and starting to modularize the code. This is an ongoing effort as there is still a lot to do, but hopefully this would motivate some to contribute ;)

An important note though: the application ID has changed and is now io.github.mightycreak.Diffuse.

Added:

• New icon and in SVG now
• Started to modularize the code

Changed:

• Changed AppID to io.github.mightycreak.Diffuse (as advised in the Flatpak documentation)
• Renamed directory `translations/` to `po/`
• Now uses POTFILES.in to list the files to translate
• Translation strings are no longer sorted alphabetically, this will help when there will be several files in POTFILES.in
• Updated the documentation and script in the `po/` directory
• Add .desktop translations in .po files

Fixed:

• Fixed some GTK deprecation warnings

Mainly under the hood changes in this release, so nothing really visible to the users in this version. That said, I figured it was a long time since the last release (4 months ago) and, as promised, I want Diffuse development to be a bit more active and iterative.

Apart from the maintenance changes 🧰, I think the main improvement is that Diffuse will soon be available through Flathub!

Added:

• New Flatpak package, published on Flathub: com.github.mightycreak.Diffuse

Changed:

• Replace old install.py with the more standard Meson
• Remove u string prefixes since Python 3 is in UTF-8 by default
• Replaced some interpolation operators (%) for the f string prefix
• Use the window scale factor for the icons generation

Here is the v0.5.0. Unintentionally, this release happens exactly 6 years after the previous v0.4.8 release!

There is a lot to do on this application, and some features didn't make the release. The main one being the Windows installers. I think 6 years is too long to continue to wait until this bug is fixed. The Python scripts should work on Windows, but no executable is produced (yet) with the release.

Other than that, Diffuse v0.5.0 is now officially compatible with Python 3 and GTK 3! And it is synced to the latest commits from upstream (which were never released).

The next version will not take 6 years, I promise you! 😄

Added:

• Added Pedro Albuquerque's Portuguese translation
• Added Åke Engelbrektson's Swedish translation
• Added Guillaume Hoffmann's Darcs support improvements
• Added Akom Chotiphantawanon's Thai translation
• Added support for Git submodules
• Added a preference and command line option to specify the version control system search order
• Added .editorconfig file
• Added .gitignore file
• Added message when removing files during uninstallation
• Added Python script to update all the translation files at once

Changed:

• Convert to Python 3
• Convert to GTK 3
• Updated Python highlighting for Python 3 grammar
• Updated copyrights years and authors
• Improve Spanish translation
• Convert translation README to MarkDown
• Updated all the translation files

Fixed:

• Fixed wrong icons directory for gtk-update-icon-cache
• Fixed missing directories when uninstalling
• Fixed bug introduced by r420 with RCS VCS
• Fixed broken drag'n'drop since migration to Python3/GTK3
• Fixed error when using '-m' in an SVN repo