UrlHelper::rewrite_relative: use base URL path if relative url path is not absolute (experimental)

Currently translated at 100.0% (660 of 660 strings)

Translation: Tiny Tiny RSS/messages
Translate-URL: https://weblate.tt-rss.org/projects/tt-rss/messages/de/

Merge pull request 'Fix:Plugins-share:init.php - site_url is NULL when share article by URL from archived articles' (#35) from kdan/tt-rss:master into master

Reviewed-on: https://git.tt-rss.org/fox/tt-rss/pulls/35

Reviewed-on: https://git.tt-rss.org/fox/tt-rss/pulls/36

Avoid "E_NOTICE (8) (classes/userhelper.php:78) Undefined index:
csrf_token" in logs.

save found youtube videos as post enclosures for af_youtube_... plugins to deal with later, if enabled

 * deprecate cdm.intermediate
 * implement lazy-load for rendered enclosures
 * simplify pack/unpack logic for articles

Currently translated at 99.8% (659 of 660 strings)

Translation: Tiny Tiny RSS/messages
Translate-URL: https://weblate.tt-rss.org/projects/tt-rss/messages/de/

Merge pull request 'FIX: public.php - Undefined index: feed_title' (#34) from ohaucke/tt-rss:public-php-fix into master

Reviewed-on: https://git.tt-rss.org/fox/tt-rss/pulls/34

Reviewed-on: https://git.tt-rss.org/fox/tt-rss/pulls/32

Merge pull request 'if backend request 'op' is empty fixed' (#27) from Cyb10101/tt-rss:cyb-backend-op into master

Reviewed-on: https://git.tt-rss.org/fox/tt-rss/pulls/27