Report notebook being processed when erroring

[kwinkunks]

To do this, I think we'd have to wrap each likely failure point -- e.g. checking for presence of data files on AWS -- in a try -- so we can give the name of the current notebook. Otherwise the error just looks like (for example):

(py39) matt@marlinspike:/local/Dropbox/dev/geocomputing$ ./geocomputing.py test geocomp-mldl
Testing geocomp-mldl. Ctrl-C to abort.
Processing notebooks +++++++++++++++++++++
Checking and downloading data ...Traceback (most recent call last):
  File "/local/Dropbox/dev/geocomputing/./geocomputing.py", line 333, in <module>
    cli()
  File "/home/matt/miniconda3/envs/py39/lib/python3.9/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/home/matt/miniconda3/envs/py39/lib/python3.9/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/home/matt/miniconda3/envs/py39/lib/python3.9/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/matt/miniconda3/envs/py39/lib/python3.9/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/matt/miniconda3/envs/py39/lib/python3.9/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/local/Dropbox/dev/geocomputing/./geocomputing.py", line 69, in test
    _ = build_course(course, clean=True, zip=False, upload=False, clobber=True)
  File "/local/Dropbox/dev/geocomputing/./geocomputing.py", line 137, in build_course
    raise Exception(f"Missing data URL: {url}")
Exception: Missing data URL: https://geocomp.s3.amazonaws.com/data/Panoma_Field_Permian_data.csv

Should be much easier with #1