[Feature request] Jade output filenames based on doctype

[chris-scheurle]

I use Jade not only for html documents but also to create other file formats, like plain xml or svg.

Right now, for every such document, I have to change the output filename manually, which sometimes can be a real pain in the ****. :grimacing:

:arrow_right: It would be nice, if in the language settings for Pug/Jade, beneath the "Output Filename" text field, there was some checkbox "Overwrite default extension according to files' doctype declaration". :smile: