Features
* Linux apps can now be packaged in Flatpak format. (359)
* SDKs, tools, and other downloads needed to support app builds are now stored in an OS-native user cache directory instead of `~/.briefcase`. (374)
* Windows MSI installers can now be configured to ask the user whether they want a per-user or per-machine install. (382)
* The console output of Windows apps is now captured and displayed during `briefcase run`. (620)
* Windows apps are now packaged with a stub application. This ensures that Windows apps present with the name and icon of the app, rather than the `pythonw.exe` name and icon. It also allows for improvements in logging and error handling. (629)
* Temporary docker containers are now cleaned up after use. The wording of Docker progress messages has also been improved. (774)
* Users can now define a `BRIEFCASE_HOME` environment variable. This allows you to specify the location of the Briefcase tool cache, allowing the user to avoid issues with spaces in paths or disk space limitations. (789)
* Android emulator output is now printed to the console if it fails to start properly. (799)
* `briefcase android run` now shows logs from only the current process, and includes all log tags except some particularly noisy and useless ones. It also no longer clears the Logcat buffer. (814)
Bugfixes
* Apps now have better isolation against the current working directory. This ensures that code in the current working directory isn't inadvertently included when an app runs. (662)
* Windows MSI installers now install in `Program Files`, rather than `Program Files (x86)`. (688)
* Linuxdeploy plugiuns can now be used when building Linux AppImages; this resolves many issues with GTK app deployment. (756)
* Collision protection has been added to custom support packages that have the same name, but are served by different URLs. (797)
* Python 3.7 and 3.8 on Windows will no longer deadlock when CTRL+C is sent during a subprocess command. (809)
Misc
* 778, 783, 784, 785, 786, 787, 794, 800, 805, 810, 813, 815