Tribler 7.0.0

What's new in this version:

- Redesigned the user interface and dropped wxPython in favor of PyQt
- Made a clean separation between the user interface and the Tribler coreThis significantly improves speed and stability
- Deployed a blockchain fabric within Tribler to keep track of bandwidth contributions
- Added new RESTful API for developers
- Created a twistd plugin, allowing users to run Tribler without a user interface
- Refactored our test suite significantlyUnit tests execute faster now and are more reliable
- Improved the build process of the Tribler executable on Windows and macOS
- Updated dependencies of Tribler to the latest versions
- Fixed compatibility with latest versions of libtorrent
- Improved integration of the Twisted framework with the Tribler codebase
- Executables on Windows are now signed
- Fixed many race conditions due to context switches between various threads
- Improved error reporting functionality when Tribler crashes
- Improved the debug panel and expanded it with additional information
- Fixed various memory leaks when running Tribler for several hours or days
- Improved Unicode support
- Fixed various bugs when receiving malformed packets from other peers