* PM Maliki seeks third term following U.S. withdrawal
* Sunni parties complain of voting problems
* Security calm in Baghdad but country beset by conflict
By Ned Parker and Ahmed Rasheed
BAGHDAD, April 30 (Reuters) - Iraq held a democratic vote to choose a leader with no foreign troops present for the first time on Wednesday, as Shi'ite Prime Minister Nuri al-Maliki sought to ...