mca: Fix calculation of needed sector count

With a data length of 4092, 2 sectors were required instead of 1

save/region/mca.go

@@ -4,6 +4,7 @@ import (
 	"encoding/binary"
 	"errors"
 	"io"
+	"math"
 	"os"
 	"time"
 )
@@ -152,7 +153,7 @@ func (r *Region) ReadSector(x, z int) (data []byte, err error) {
 
 // WriteSector write Chunk data into region file
 func (r *Region) WriteSector(x, z int, data []byte) error {
-	need := int32(len(data)+4)/4096 + 1
+	need := int32(math.Ceil(float64(len(data)+4) / 4096))
 	n, now := sectorLoc(r.offsets[z][x])
 
 	// maximum chunk size is 1MB