Added header, headerHeight. renderFooter and renderHeader are now passes through when specified
Added header, headerHeight. renderFooter and renderHeader are now passes through when specified

dalhorinek/react-native-letterlistview,deanmcpherson/react-native-selectablesectionlistview,johanneslumpe/react-native-selectablesectionlistview,ianhowe76/react-native-alphabetlistview,xinlc/react-native-selectablesectionlistview