added functionality to delete old worlds to mcbe-backup

src/mcbe/assets/bin/mcbe-backup

@@ -69,6 +69,13 @@ done
 # tell minecraft it can resume
 mcbe-exec save resume
 
+# delete old inactive worlds
+ls -w 1 | grep -v -E "^$world\$" | while read -r line; do
+    if [[ ! -e "$worlds_dir/$line" ]]; then
+        rm -r "$line"
+    fi
+done
+
 # copy inactive worlds
 ls -w 1 "$worlds_dir" | grep -v -E "^$world\$" | while read -r line; do
     rsync -a "$worlds_dir/$line" ./