modified generated HTML files by downloading CDN-loaded assets

[wki]

Hi,

maybe I am doing something wrong. But when opening generated HTML files in the output-directory directly in a browser fails because some JavaScript or CSS Assets are loaded without a protocol. This requires being online when viewing a presentation and requires starting a server.

By downloading all CDN-loaded assets into the output-directory, all presentations may be viewed offline and without running a web server.

This simple patch modifies the HTML files after their generation. Maybe not perfect but usable.

Forgive me if my beginners-F#-Style is not perfect, too.

[isaacabraham]

This would be awesome, it's something I've wanted solved for ages!

[forki]

@haf howdoes this relate to your recent work?

[haf]

It's duplicate work to my PR.

[wki]

if this thing will be solved by another PR, then please silently ignore my PR.

[haf]

@wki I think the only part left for the other #104 PR to merge is a review actually... I was like a truck truckin' along that ran out of gas and needs to get some help to go to the finish line ;) If you'd be up for it, it would be much appreciated.