Introduced CMake option OSG_PROVIDE_READFILE option that defaults to ON, but when switched to OFF disables the building of the osgDB::read*File() methods,

forcing users to use osgDB::readRef*File() methods.  The later is preferable as it closes a potential threading bug when using paging databases in conjunction
with the osgDB::Registry Object Cache.  This threading bug occurs when one thread gets an object from the Cache via an osgDB::read*File() call where only
a pointer to the object is passed back, so taking a reference to the object is delayed till it gets reassigned to a ref_ptr<>, but at the same time another
thread calls a flush of the Object Cache deleting this object as it's referenceCount is now zero.  Using osgDB::readREf*File() makes sure the a ref_ptr<> is
passed back and the referenceCount never goes to zero.

To ensure the OSG builds when OSG_PROVIDE_READFILE is to OFF the many cases of osgDB::read*File() usage had to be replaced with a ref_ptr<> osgDB::readRef*File()
usage.  The avoid this change causing lots of other client code to be rewritten to handle the use of ref_ptr<> in place of C pointer I introduced a serious of
templte methods in various class to adapt ref_ptr<> to the underly C pointer to be passed to old OSG API's, example of this is found in include/osg/Group:

    bool addChild(Node* child); // old method which can only be used with a Node*

    tempalte<class T> bool addChild(const osg::ref_ptr<T>& child) { return addChild(child.get()); } // adapter template method

These changes together cover 149 modified files, so it's a large submission. This extent of changes are warrent to make use of the Object Cache
and multi-threaded loaded more robust.



git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/branches/OpenSceneGraph-3.4@15165 16af8721-9629-0410-8352-f15c8da7e697

include/osg/Geode

@@ -49,6 +49,8 @@ class OSG_EXPORT Geode : public Group
         */
         virtual bool addDrawable( Drawable *drawable );
 
+        template<class T> bool addDrawable( const ref_ptr<T>& drawable ) { return addDrawable(drawable.get()); }
+
         /** Remove a \c Drawable from the \c Geode.
           * Equivalent to <tt>removeDrawable(getDrawableIndex(drawable)</tt>.
           * @param drawable The drawable to be removed.
@@ -57,6 +59,8 @@ class OSG_EXPORT Geode : public Group
         */
         virtual bool removeDrawable( Drawable *drawable );
 
+        template<class T> bool removeDrawable( const ref_ptr<T>& drawable ) { return removeDrawable( drawable.get() ); }
+
         /** Remove <tt>Drawable</tt>(s) from the specified position in
           * <tt>Geode</tt>'s drawable list.
           * @param i The index of the first \c Drawable to remove.
@@ -73,6 +77,8 @@ class OSG_EXPORT Geode : public Group
         */
         virtual bool replaceDrawable( Drawable *origDraw, Drawable *newDraw );
 
+        template<class T, class R> bool replaceDrawable( const ref_ptr<T>& origDraw, const ref_ptr<R>& newDraw ) { return replaceDrawable(origDraw.get(), newDraw.get()); }
+
         /** Set \c Drawable at position \c i.
           * Decrement the reference count origGSet and increments the
           * reference count of newGset, and dirty the bounding sphere
@@ -85,6 +91,8 @@ class OSG_EXPORT Geode : public Group
         */
         virtual bool setDrawable( unsigned int i, Drawable* drawable );
 
+        template<class T> bool setDrawable( unsigned int i, const ref_ptr<T>& drawable ) { return setDrawable(i, drawable.get()); }
+
         /** Return the number of <tt>Drawable</tt>s currently attached to the
           * \c Geode.
         */
@@ -108,6 +116,8 @@ class OSG_EXPORT Geode : public Group
             return false;
         }
 
+        template<class T> bool containsDrawable(const ref_ptr<T>& drawable) const { return containsDrawable(drawable.get()); }
+
         /** Get the index number of \c drawable.
           * @return A value between 0 and <tt>getNumDrawables()-1</tt> if
           *         \c drawable is found; if not found, then
@@ -118,6 +128,8 @@ class OSG_EXPORT Geode : public Group
             return getChildIndex(drawable);
         }
 
+        template<class T> unsigned int getDrawableIndex( const ref_ptr<T>& drawable ) const { return getDrawableIndex(drawable.get()); }
+
         /** Compile OpenGL Display List for each drawable.*/
         void compileDrawables(RenderInfo& renderInfo);