Plugin: Sharing news and feeds with other friends who use Liferea

[sjehuda]

Inspired by ticket #1343

About

Plugin to connect Liferea to XMPP account and share news items and news sources with contacts that appear in roster (i.e. contact list).

Realization

1. Lars, Herman, and Schimon have Liferea.
2. All of them are communicating in the XMPP network.
3. Herman finds an interesting news feed.
4. Herman right-clicks on the feed and selects "Share...".
5. A dialog with contacts appear (contacts are stored on XMPP server).
6. Herman selects Lars, Schimon and Christopher.
7. Lars and Schimon receive a notification from Liferea about a new source from Herman.
8. Christopher is connected to XMPP, but his computer is turned off, so he receives a headline message (this means that it appears as an announcement-style message in a single window) which says:

Title: Liferea Share

Greetings Christopher!

I want to share with you this news URL which I deem as of interesting.

Kindly,
Herman

• This is an automated message made by Liferea.

Note: "deem as of interesting" may be an optional "reason"; without it, the message would be "I want to share with you this news URL", without "which I" etc.