Summer of bugfixes

• Better error messages when fetching data from Twitter or Mastodon fails
• Fixed deletion of old favorites on Mastodon

Bugfix release

Fix registration error with saving TOML configuration.

Bugfix release

Fixed error with Mastodon posts starting with umlauts.

Bugfix release

• Improved Twitter sync handling when there are lots of replies to be ignored
• Prevent double posting without panics
• Update Mammut upstream library