Apply a simple pimpl idiom and rename the old Impl to make it non-Impl.

The old Impl instance is ref-counted, which I'd like to convert to using
boost::intrusive_ptr.  But to make it happen, we need to really hide this
from public header...

Change-Id: I1f1e9e500f2112eea04e3e6d661a7dfa74655c62

include/editeng/outlobj.hxx

@@ -26,12 +26,11 @@
 #include <rsc/rscsfx.hxx>
 
 class EditTextObject;
-class ImplOutlinerParaObject;
 
 class EDITENG_DLLPUBLIC OutlinerParaObject
 {
-private:
-    ImplOutlinerParaObject*        mpImplOutlinerParaObject;
+    struct Impl;
+    Impl* mpImpl;
 
     void ImplMakeUnique();