ENHANCEMENT: ready for Nextcloud 11
ENHANCEMENT: faster bookmarking due to making less requests
ENHANCEMENT: some under the hood overhaul
FIX: info.xml metadata was cleaned of deprecated elements and updated (thx @eppfel)
FIX: no hardcoded naming of the underlying server software (also thx @zerojay)
FIX: avoid 500 (server error) when accessing bookmarks or using bookmarklet while being logged out
FIX: don't fail adding a bookmark on cURL error 18
FIX: do not fail adding a bookmark when the website is unavailable to the server
NOTE: I do not have access to the original bookmarks app on the ownCloud app store anymore. The app will be definitely available via the Nextcloud app store (default in Nextcloud 11).