This commit adds support to add Lemmy RSS feeds to FeedDeck. A user can
provide the url of an Lemmy instance, the url of a community or of an
user.
The special thing of the Lemmy source in opposite to the normal RSS
source is, that we parse the provided link form a feed item, to check if
it contains a image, video or YouTube url, to apply some special
formatting.
8c88ece3dc
