Use hardlinks to create copies for performance boost

[mlissner]

I made a change on my branch, just as a test

mlissner@ba5829d

Immediately my "build" times for my blog came down by many seconds, even when using --write-selected.

I recognize this probably isn't platform independent (an assumed goal of Pelican?), so I'll need to tweak it, but any reason we haven't done something like this already? Seems like low-hanging fruit so want to make sure I'm not missing something.

[smartass101]

There already is an issue for this: #1042
Your approach unfortunately does not address the whole issue, have a look at utils.copy.
We'd welcome your contribution in the form of expanding on the work done in the referenced issue. Not that you need to take the same approach (maybe there is a better one), but please DRY and have a look what needs to be done.

Platform portability is an issue of course, but if it's clearly documented and will fall back to copying on platforms without linking support, that would be ok.