Extraced from r14281 from the younes branch.

Extraced from r14281 from the younes branch.

* BufferView, BufferView::pimpl:
	- metrics_info_: private variable holding ViewMetricsInfo
	- viewMetricsInfo(): accessor function
	- updateMetrics(): renamed from metrics(), sets metrics_info_
	- update(): change to use updateMetrics()

* frontends/WorkArea:
	- redraw(): get the ViewMetricsInfo through accessor to BufferView.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@14331 a592a061-630c-0410-9148-cb99ea01b6c8