* Add hard_link_static config option.
* Copy or hardlink file depending on an argument.
Modify the call sites for `copy_file` to account for the extra argument.
* Plug the config setting through to copy_file.
Don't apply the config option to theme's static directory.
* Update documentation.
* Backticks make no sense in this comment.
* Addressing PR comments.
* Be consistent with argument naming.