ui: manage logger instances and event filtering by core ui
The setup code in blackbox needs more tweaks since it has lots of black
magics. I'll fix them by follow-up patches.
To be clear, the goal of this series is to provide a proper way for command
server to install its own logger. I need it to debug in-memory repository
cache.
max_width = 79
wrap_comments = true
error_on_line_overflow = true