addPts method
Implementation
void addPts(List<Coordinate> pt, bool isForward) {
if (isForward) {
for (int i = 0; i < pt.length; i++) {
addPt(pt[i]);
}
} else {
for (int i = pt.length - 1; i >= 0; i--) {
addPt(pt[i]);
}
}
}