Displaying text structure

This is somehow related to ~~#226~~. djview4 "understand" the underlying text structure and displays e.g. word borders in the status bar, such a feature would be usefull also in djview4poliqarp. It would be nice to obey such word/line borders when marking text for copying e.g. into the Edit dialog.

There is also a feature, which I requested but Bottou refused to implement it: displaying the full page structure (division into columns etc.).