Fix DOMDocument usage on PHP 8.2
Manually activate libxml external entity resolver so that we are able to load remote URLs with DOMDocument Resolves: https://github.com/cweiske/phorkie/issues/26
add fixme
fix gist.github.com clone urls
extract gist titles
Fix #43: gist.github.com URLs with usernames
first work on remote fork notifications with linkback (webmention/pingback)