Reorganised the Group::removeChild and Geode::removeDrawable methods so

that removeChild(Node*), removeChild(uint) and equivilant Geode methods are
now inline methods, not designed to be overriden, and seperated out the
multiple remove method to be called removeChildren(uint, uint) which is
now the only virtual method.  There removeChildren is now the method to
override in subclasses.

This reorganisation requires some call code to be rename removeChild usage
to removeChildren.

include/osg/Switch

@@ -49,9 +49,7 @@ class OSG_EXPORT Switch : public Group
 
         virtual bool insertChild( unsigned int index, Node *child, bool value );
 
-        virtual bool removeChild( Node *child );
-
-        virtual bool removeChild(unsigned int pos,unsigned int numChildrenToRemove=1);
+        virtual bool removeChildren(unsigned int pos,unsigned int numChildrenToRemove);
 
 
         void setValue(unsigned int pos,bool value);