More than 1,740 people were killed or injured in Haiti from July to September, a nearly 30% increase over the previous trimester, according to the latest numbers released Wednesday by U.N. officials.The surge in violence comes as gangs seize control of 85% of the capital of Port-au-Prince — up from 80% — while a U.N.-backed mission led by Kenyan police to quell gang violence struggles with a lack of funding and personnel, prompting calls for a U…