Investigate why the spellchecking checks are slow

[PCManticore]

pylint-dev/astroid#579 (comment) this comment mentioned that disabling the spellchecking checks improvement the runtime of pylint from half an hour to ~10 minutes, which suggests that something might be completely off with the spellchecking. We should investigate to see why is that, and if we can find that these are hurting the performance, we should either disable the spellchecking by default (as we do for the Py3k porting checks), or we should move them to an extension, so that they can be enabled explicitly by the user.

[svmhdvn]

I can take a closer look at this, we're running into pylint performance issues as well.

[robin-wayve]

I didn't know these checks existed and have never actually seen them fail a check (although I'm almost certain our codebase has plenty of spelling errors in comments and docstrings).

Maybe pylint could consider dropping these checks in a future major version and recommending an alternative like codespell instead?

[Pierre-Sassoulas]

I think python-enchant need to be installed for those checks to run.