- InsetQuotes updates the inset cache

- InsetQuotes updates the inset cache
- Do not use the nullpainter for the rows outside the screen, because the nullpainter does not calculate the width of text, and thus the metric entries in the inset cache are completely wrong, causing assertions when using for instance page up or page down into an inset. This fixes the dreading assertion on navigation in the user guide, and elsewhere

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@15455 a592a061-630c-0410-9148-cb99ea01b6c8