- also move SwContentNode and SwTextNode from
  Modify to SwClientNotify
- this removes the last public use of SwDepend, which should now become
  an implementation detail of WriterMultiListener

Change-Id: I5ae3a7a091fb2b6bb3bce44a0adc4f41f07a0c30
Reviewed-on: https://gerrit.libreoffice.org/53835Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Björn Michaelsen <bjoern.michaelsen@libreoffice.org>