Add an updateParagraph signal, take the opportunity to make a couple of

Add an updateParagraph signal, take the opportunity to make a couple of
cosmetic name changes to existing signals.
updateParagraph signal emitted from BufferView::fitCursor().
Add crude machinery to deal with it in the xforms Paragraph dialog.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@2130 a592a061-630c-0410-9148-cb99ea01b6c8