A schedule per location, and locations backed up one after the other

Off, once a day or every N hours from a time, each in its own time zone. Existing locations
keep the time that held for all of them. A backup that has to wait shows as queued, and its
restore point has the time it really began.

src/api.js

@@ -34,7 +34,7 @@ export default {
 	setTargetLimit: (id, maxGb) => call('put', `/targets/${id}/limit`, { maxGb }),
 	startBackup: (targetId, label) => call('post', '/backups', { targetId, label }),
 	tick: () => call('post', '/tick'),
-	setSchedule: (time, timezone) => call('put', '/schedule', { time, timezone }),
+	setTargetSchedule: (id, schedule, timezone) => call('put', `/targets/${id}/schedule`, { schedule, timezone }),
 	snapshots: (targetId) => call('get', `/targets/${targetId}/snapshots`),
 	setSnapshotNote: (targetId, snapshotId, note) => call('put', `/targets/${targetId}/snapshots/${snapshotId}/note`, { note }),
 	setSnapshotPinned: (targetId, snapshotId, pinned) => call('put', `/targets/${targetId}/snapshots/${snapshotId}/pin`, { pinned }),