Style Checker for Sphinx docs

[Sudhanshu Mishra]

Hi all

This is a nice tool to check following styles for docs:

- lines should not be longer than 79 characters - D001
  - exception: line with no whitespace except maybe in the beginning
  - exception: line that starts with '..' -- longer directives are allowed,
    including footnotes
- no trailing whitespace - D002
- no tabulation for indentation - D003
- no carriage returns (use unix newlines) - D004

Although we already have tool to strip whitespaces, we can use it for other three things.

Regards

Sudhanshu Mishra