[FEATURE] save PDF page/location

If I do not use my pdf except through Incremental Reading in the queue, there will be no problem. But if I open the PDF outside of the IR queue to see another page and eventually make some highlights, the next IR review will point to this new location, instead of that of the last IR section.

It would be amazing if IR plugin could save the location in the PDF when I press "Next", in order to ensure that in the next IR section I will start reading in the exact location I stopped reading that PDF in the last IR section.