Configure Nextcloud

- some keys in ~/.config/Nextcloud/nextcloud.cfg are set by
  the machine automatically when in use
- integrate Nextcloud in XDG user directories
- make Nextcloud run on login in Gnome
- add `run-private-scripts` utility to run shell scripts
  stored in the Nextcloud

.config/Nextcloud/sync-exclude.lst

@@ -0,0 +1,49 @@
+# This file contains fixed global exclude patterns
+
+*~
+~$*
+.~lock.*
+~*.tmp
+]*.~*
+]Icon\r*
+].DS_Store
+].ds_store
+*.textClipping
+._*
+]Thumbs.db
+]photothumb.db
+System Volume Information
+
+.*.sw?
+.*.*sw?
+
+].TemporaryItems
+].Trashes
+].DocumentRevisions-V100
+].Trash-*
+.fseventd
+.apdisk
+.Spotlight-V100
+
+.directory
+
+*.part
+*.filepart
+*.crdownload
+
+*.kate-swp
+*.gnucash.tmp-*
+
+.synkron.*
+.sync.ffs_db
+.symform
+.symform-store
+.fuse_hidden*
+*.unison
+.nfs*
+
+My Saved Places.
+
+\#*#
+
+*.sb-*