Wits in the Phoenix Park Garda Depot years ago used to quip that planning for security set-pieces was easy: Just take down the file on the Thatcher-Haughey summit of 1980 in Dublin and repeat.  But there is little in the wisdom of the past to guide the security services as Ireland assumes the presidency of the Council of the European Union. The security scenario being faced by An Garda Síochána and the Defence Forces is without precedent.  The world was a very different place when Ireland last held the presidency. It was 2013. Barack Obama was in the White House.…