COLUMBIA, S.C. — Early voting in South Carolina’s Republican presidential primary started Monday. Any of the state’s 3.1 million registered voters who did not participate in the Feb. 3 Democratic presidential primary is eligible to cast a ballot in the GOP primary. State GOP Chairman Drew McKissick has estimated about 1 million people could vote in the Feb. 24 primary. Before heading to the polls, here’s what to know. Polling places may have been combined. County election commissions have the flexibility to combine locations in primary in order to save money, the state election commission said…