Multi-module KeyData interface

[takluyver]

This brings an API similar to KeyData to multi-module detector data, so instead of agipd.get_array('image.data') you can do something like agipd['image.data'].xarray(). I hope this will make using EXtra-data more consistent, at least once people are used to using these newer APIs.

This also adds the ability to get an unlabelled numpy array for multi-module detector data; previously you had to get an xarray, even if you didn't want the labels. I still think dimension labels are a good idea, but xarray is certainly an extra level of complexity, and many people are more familiar with numpy arrays.

Finally, this changes how Dask arrays are created for multi-module data - rather than making chunks directly based on the files, so each frame is split across multiple chunks, it now uses the .split_trains() method to break data into chunks to load, so each Dask chunk spans all modules. This simplifies the task graph for the common case where you want to process data frame-wise with all modules together. I had hoped that this would solve all our issues with Dask and make #333 obsolete, but unfortunately that doesn't seem to be the case - we might want some variant of that PR as well.

[lgtm-com]

This pull request introduces 1 alert when merging d750db7 into 1ba78dd - view on LGTM.com

new alerts:

• 1 for Module is imported with 'import' and 'import from'

[lgtm-com]

This pull request introduces 1 alert when merging a138efa into 1ba78dd - view on LGTM.com

new alerts:

• 1 for Module is imported with 'import' and 'import from'

[lgtm-com]

This pull request introduces 1 alert when merging fd4ad9a into 1ba78dd - view on LGTM.com

new alerts:

• 1 for Module is imported with 'import' and 'import from'

[philsmt]

Thanks for this nice PR. Indeed the components API did feel slightly out of touch, especially when using them the first time after KeyData got introduced. This will nicely fill the gap.

Given the fairly complex axes-shifting and index-juggling machinery in here, I don't feel able to properly review logic as such. But I tried to give some constructive comments or ideas here or there.

[lgtm-com]

This pull request introduces 1 alert when merging 8c1b922 into 9b36ce4 - view on LGTM.com

new alerts:

• 1 for Module is imported with 'import' and 'import from'

[philsmt]

Thank you, LGTM!

[takluyver]

Thanks for the review 👍