mutt: change filtering DSL for better readability
mutt: change filtering DSL for better readability

Move the description to the top, reducing the need for comments.

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent