Changes:
- Automated checks for links can now be disabled to prevent ongoing "broken" links (#93)
- New user setting: open links in new tabs (#97)
- Adds an update check based on Github releases to the system settings page (#96)
- Entries can now be deleted from the edit screens
- Overhauled dark theme and many UI corrections and improvements
- Update to Laravel 7, minimum required PHP version is now 7.2.5
- Moved from Guzzle to the Laravel-own HTTP helper, improved the testing