Bratislava (AFP) - German Chancellor Angela Merkel warned on Friday that the EU faces a "critical situation", as European leaders sought to plot the bloc's post-Brexit future at a summit without Britain. The 27 leaders -- minus British Prime Minister Theresa May -- gathered at Bratislava's towering castle overlooking the River Danube, determined to respond to the challenges of mass migration, security, globalisation and a stuttering economy. The aim was to thrash out a "roadmap" of reforms during talks in the Slovak capital's towering hilltop castle, and a boat trip down the Danube. Merkel said the bloc simply had to...