Remove private Qt headers from Designer for LSB [as much as feasible]

8.2.2007 Designer will not be the LSB test app.

1) Existing Issues (4.5, 1.9.2008):
----------------------------

lib/shared/qdesigner_widgetitem.cpp:21:#include <private/qlayout_p.h>

• [new API] Sets/Resets QWidgetItem creation hook and derives from QWidgetItemV2 (could be QWidgetItem)

lib/shared/stylesheeteditor.cpp:42:#include "private/qcssparser_p.h"

• [new API] Validates Style sheet

lib/uilib/abstractformbuilder.cpp:46:#include <private/qlayout_p.h>

• [new API] Invokes QWidgetItem creation method to obtain a widget item

components/formeditor/qdesigner_resource.cpp:76:#include <private/qlayoutengine_p.h>

• [new API] uses qSmartMinSize

2) Things to come:
-----------------------------

• We want a widget painting hook that is invoked with its QPainter after that widget has painted to be able to paint grids , utility lines on top of it without
  [significant] loss of performance or [backing-store] caused artifacts

• We want a [computationally inexpensive] method to tell whether an area of a widget is a "Passive interactor" , that is, whether Designer should refrain
  from blocking events in that area (for example, a toolbar handle, scrollbar handle, etc).
  QUestion is, whether a simple bool is sufficient .. enumeration instead?