Log Message:
libmpdclient: Update to 2.18

libmpdclient 2.18 (2020/01/20)
* more out-of-memory checks
* partition: add mpd_recv_partition()
* support MPD protocol 0.21
 - "oneshot" single state
* support MPD protocol 0.22
 - status: add mpd_status_get_partition()
 - commands "delpartition", "moveoutput"