Moving Constructor definition to the top like a Function definition

[ankit-maverick]

I would like to know if there is any specific reason for displaying the constructor definition at the bottom unlike a normal function definition. Currently it is less user-friendly to check up the default values of the arguments in the constructor. For example : scikit-image/scikit-image#885 (comment)

[Carreau]

Hum... even wondering if this is not a regression...
I'll mark as 2.0, but not sure it will make it through.

[takluyver]

I don't think this is a regression - I think we've always printed the class docstring above the constructor info. We have to guess what is most likely to be useful to the user, and it's not clear that putting constructor info above the class docstring is better.

[Carreau]

Oh, I read it was the constructor signature.

Maybe we can peek at which one have the less lines. If constructor have less lines, it is probably just info on the signature right ?

[takluyver]

It is constructor signature in the example shown, but we group constructor info - docstring, signature, etc. - together.

[minrk]

#5285 makes the proposed change, and should improve the output for classes and callable objects