[Freeciv-Dev] Marco Polo's Embassy

[Rizos Sakellariou <rizos@xxxxxxxxxxx>]

With the ever increasing diplomacy capabilities in freeciv,
i think it's time to include the Marco Polo's Embassy wonder. 
The changes needed in the code are minimal, but can someone
check what is the behaviour of civ when the wonder becomes
obsolete? Does it mean _only_ that the wonder won't have the
desired effect (as usual with obsolete wonders), or does it
also mean that any player owning the wonder will lose all
embassies established as a result of this wonder? I suspect
that the former is more likely but this needs to be confirmed.

--rizos

Specifications of the wonder:
- Can be built after Trade has been discovered (cost 200).
- The player who owns it gets an embassy with all the 
  remaining players.
- Becomes obsolete with Communism (effect to be clarified).