The idea is that if you have your cursor at the begining of a Calc document, and you scroll down a
lot, then search, then it's annoying that search jumps back to the start of the document for the
first hit.

Add an optional way to provide what is the starting point of such a search, so we can have "when
nothing is selected, then search from the top left corner of the visible area".

Change-Id: I22624dd52a093759d46541e003d838aeb0db943f