A surge of diplomacy and an outburst of violence in the days since world powers reached a deal with Iran illustrate both the promise and the peril of what could be the start of a more peaceful era in the Middle East — or the beginning of a new round of bloodletting. The announcement of the six-month accord on Iran’s nuclear program, hailed by President Obama as an opportunity to reverse decades of hostility between Washington and Tehran, has quickly been followed by indications of the deal’s potential to unlock other regional conflicts. An anti-Government protester raises his fist after getting into the compound of Government House in Bangkok, Thailand Tuesday, Dec. 3 2013. Anti-government protesters swarmed into the Thai prime minister’s office compound Tuesday as police stood by and watched, allowing them to claim a symbolic victory after three days of bitter clashes. ([…]