Add train entrypoint

[adamjstewart]

Python has a concept of "entrypoints" that allow you to do something like:

$ torchgeo train conf=...

and run train.py. We should look into incorporating this. We'll also want to install the conf files somewhere and teach TorchGeo how to find them. The tricky part is making both of the following work:

$ python train.py conf=...
$ torchgeo train conf=...

since both the training file and the conf files will be in different locations in those two cases.

[adamjstewart]

Some docs on how to implement this: https://python-packaging.readthedocs.io/en/latest/command-line-scripts.html

[adamjstewart]

More docs:

• python-packaging
• python __main__
• setuptools entry points
• LightningCLI API
• LightningCLI Tutorials