Update CSS selectors and control logic.
Update CSS selectors and control logic.

Github has updated their DOM and CSS, which unless I'm mistaken, simplifies this script's job considerably.

Simplifies the jQuery selectors and click logic to match Github's new DOM and more-universally-available `soft-wrap` class. Updates the [Soft wrap] button's CSS to match Github's current presentational style.

Also adds a `@match` annotation, which seems to make recent Chrome versions happier, and `@author` information.
luiz/github-soft-wrap,Prokochalov77/github-soft-wrap