Free BufferView from LyXView!

Free BufferView from LyXView!

* BufferView
  - layoutChanged: new boost signal.
  - LyXView owner(), owner_: deleted

* text3.C
  - emit BufferView::layoutChanged instead of calling LyXView::setLayout directly
  - LFUN_MOUSE_RELEASE: delete LyXView updateMenubar() and updateToolbars() direct calls.
    The update is of both bars is done in WorkArea::dispatch().

* WorkArea.C
  - dispatch(): add LyXView updateMenubar() call.

* LyXView
  - connects to BufferView::layoutChanged directly to Toolbars::setLayout()
  - setLayout(): deleted.

* qt4/GuiImplementation: modify BufferView construction (without LyXView).

All other files: cleanup header declaration of LyXView.h

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@15153 a592a061-630c-0410-9148-cb99ea01b6c8