Because merge_links() use the index, we need to get the new_links() _before_ we manipulate the index with write_links_index(). This has the negative side effect that the "Adding X new links ..." will output twice (because we execute merge_links() twice. For that, we only output stuff when the only_new is not set.
When importing a huge list of links periodically (from a big dump of
links from a bookmark service for example) with a lot of broken links,
this links will always be rechecked. To skip this, the environment
variable ONLY_NEW can be used to only import new links and skip the rest
altogether. This partially fixes#95.
