sw: convert more SwTxtNode stuff to OUString
sw: convert more SwTxtNode stuff to OUString

Change-Id: Ic853af7f66d970d7acfcb7d39effc738cbb7f68d

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core