Add alignWithTop flag to indicate rect should be scrolled to top of view

This mirrors the HTML flag of the same name:
https://developer.mozilla.org/en-US/docs/Web/API/element.scrollIntoView

This feature is unused within WebODF, but I have need for it externally for a custom find panel. The code change seemed simple enough so I have raised a PR here, feel free to close however if this is undesirable.

For reviewing and testing purposes, I manually modified the ``gui.Caret`` scrollIntoView call to specify the new flag as true, and then ensured the caret was always scrolled to the top (it makes for a very jarring editing experience by the way!).