Close remaining review gaps

- restore runs from the web are created under the location's exclusive
  lock, like backup runs
- raw restore writes to an unpredictable temporary name opened with
  exclusive create (never follows a planted symlink) and validates the
  path prefix; the restore service rejects non-canonical paths instead
  of trimming them (occ normalises user input before calling it)
- restore jobs report progress every minute, so a long restore is not
  taken for a dead one
- README: Object Lock turns deletions into delete markers

appinfo/info.xml

@@ -5,7 +5,7 @@
     <name>NG Backup</name>
     <summary>Encrypted, incremental backups of your Nextcloud with restore from the web interface</summary>
     <description><![CDATA[Work in progress, not ready for use.]]></description>
-    <version>0.0.12</version>
+    <version>0.0.13</version>
     <licence>agpl</licence>
     <author>Dillard Blom</author>
     <namespace>NgBackup</namespace>