* use tqdm.auto in trainer
This will import the ipywidgets version of tqdm if available. This works nicely in notebooks by not filling up the log.
In the terminal it will use the same old tqdm.
We might also want to consider passing in the tqdm we want as an argument since there may be some edge cases where ipywidgets is available but the interface doesn't support it (e.g. vscode?) or isn't working. In which case people will get a warning message, but may want to configure it themselves.
* use `from tqdm.auto` in eval loop
* indents
Mike Clark