[1.7.x] Stop errors on older Spatialite versions that miss some tables
[1.7.x] Updated links for continous integration server.

Backport of 21d0ceefb5 from master
[1.7.x] Fixed broken links in docs.

Backport of 0efd72dc90 from master
[1.7.x] Fixed #21792 -- Documented Form.has_changed()

Thanks bjb at credil.org for the suggestion and
Ivan Mesic for the draft patch.

Backport of edcc75e5ac from master