PR: Use an outstream with isatty() equal to True

[eendebakpt]

This PR is work to enable colored output (by default) in the Spyder console. See spyder-ide/spyder#1917, Textualize/rich#1221, ipython/ipykernel#683

Fixes #302

It adds traitlets as a new requirement, but since ipykernel already has this as a requirement this should have little impact.

@ccordoba12

[real-yfprojects]

It adds traitlets as a new requirement, but since ipykernel already has this as a requirement this should have little impact.

Interestingly the edited file already imports and uses traitlets directly, i don't know why it isn't included in requirements already, but using traitlets is therefore not a problem in this regard.

spyder-kernels/spyder_kernels/console/start.py

Line 74 in 961e43e

from traitlets.config.loader import Config, load_pyconfig_files

Besides that I would approve this PR.

[ccordoba12]

Hey @eendebakpt, thanks for your help with this! I left an initial review for you.

[eendebakpt]

@ccordoba12 Thanks for the feedback. I addressed the comments.

[ccordoba12]

Hey @eendebakpt, I think this is almost ready! Besides the comment I left for you below, please make your branch to derive from our 2.x branch (instead of master), with the following commands:

git checkout 2.x
git checkout feat/isatty
git rebase --onto 2.x master feat/isatty
git push -f origin feat/isatty

That will allow me to include this feature in our next version of Spyder-kernels.

[ccordoba12]

Thanks for your help @eendebakpt!