Better TUI integration of FileDownloader

• fix updating of the download progress bar

• unify styling with CLI

• this also addresses some other minor issues I found along the way

• I also tried improving the delay of some logging but https://docs.python.org/3/howto/logging-cookbook.html#blocking-handlers does not seem to help and instead I believe I would need to "litter" the code with asyncio.sleep(0) calls. I am still hesitant to do that since so far not everything has to be async. Let's see...

Closes #112 (closed)