REF/CLN: pandas/io/parsers.py
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Refactor/cleanup ``pandas/io/parsers.py``
- Extract method _refresh_kwargs_based_on_dialect
- Extract method _validate_skipfooter
- Drop local variable engine_specified
- Clean-up FutureWarning issue

big picture: whats the goal? > 
> 
> big picture: whats the goal?

Extract some methods to make any further refactoring easier. > Extract some methods to make any further refactoring easier.

Is there further refactoring you have in mind? > 
> 
> > Extract some methods to make any further refactoring easier.
> 
> Is there further refactoring you have in mind?

I am still trying to figure out what the code does. By making small PRs on refactoring/cleanup I get to understand it better. Probably later I will have some suggestion on the refactoring. cc @twoertwein if any comments. LGTM, outsourcing the dialect validation makes the constructor of `TextFileReader` easier to read. Thanks @ivanovmg!