Completed implementation of interleaver. Needs testing!

common/coords.go

@@ -143,3 +143,31 @@ func TransformPlainToInterleaved(pos int64) int64 {
 func TransformInterleavedPlain(pos int64) int64 {
 	return CoordToPlain(InterleavedToCoord(pos))
 }
+
+func SelectKeySplitter(interleaved bool) KeySplitter {
+	if interleaved {
+		return InterleavedToCoord
+	}
+	return PlainToCoord
+}
+
+func SelectKeyJoiner(interleaved bool) KeyJoiner {
+	if interleaved {
+		return CoordToInterleaved
+	}
+	return CoordToPlain
+}
+
+func SelectKeyDecoder(interleaved bool) KeyDecoder {
+	if interleaved {
+		return DecodeFromBigEndian
+	}
+	return DecodeStringFromBytes
+}
+
+func SelectKeyEncoder(interleaved bool) KeyEncoder {
+	if interleaved {
+		return EncodeToBigEndian
+	}
+	return EncodeStringToBytes
+}