Implement real logging

[ChristianFeldmann]

We need a real logging framework:

• A (global) logger that collects logs with levels
• Track time, level, module, line, message
• Discard old messages (maximum nr messages, older then time)
• In the settings we should be able to enable debug logging
• Add a viewing window for the logging
• Add filtering in the viewing window (maybe)
• Add the ability to save the logs to a text file
• Switch existing logging to this logging infrastructure.