Include border when generating basin markers for watershed

[mkcor]

Description

Here I'm updating the Segment human cells in mitosis (link to stable):

• I have removed the very last figure, which I think doesn't add much value;
• I have added a few words about the watershed segmentation step;
• I have fixed the way markers are computed, so that basins touching the image border are included. You can see the difference especially if you look at the RHS vertical border of the image (see below).

Checklist

• A descriptive but concise pull request title
• Docstrings for all functions
• Unit tests
• A gallery example in ./doc/examples for new features
• Contribution guide is followed

Release note

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In the gallery example on segmenting human cells (in mitosis),
include the border when generating basin markers for watershed.

[lagru]

Thanks @mkcor. Looks already good to me so feel welcome to ignore my other minor suggestions at will. :D

[lagru]

While we are at it, do you want to switch this over to import skimage as ski? I'd happily review that. 😉

Also, while reviewing this again: is "dichotomy" a well known term? A bit of topic, but rewording that might improve the example also.

[mkcor]

While we are at it, do you want to switch this over to import skimage as ski? I'd happily review that. 😉

Done! facda52

Also, while reviewing this again: is "dichotomy" a well known term? A bit of topic, but rewording that might improve the example also.

I remember learning about this approach in my K-12 education, so I wouldn't consider it hyper-specialized...

[lagru]

It's a bit weird that the order with which the subplots are created for the over- and underestimation plot is not identical with the with index and plotted order? Maybe reorder?

[mkcor]

Sure: bf81710

[lagru]

Thanks @mkcor! Merging since this improvement to the gallery probably doesn't need a third maintainer to approve and has been open for some time.