Miscellaneous code cleanup

Description:
    - Removed two inadvertently-added Group constructors in the header file.
      There was no implementation.
    - Removed deprecated H5Location and H5Object constructors that take an
      existing ID.
    - Miscellaneous improvements in comments, including updating URLs.
Platforms tested:
    Linux/32 2.6 (jam)
    Linux/64 (jelly)
    Darwin (osx1010test)

c++/src/H5OcreatProp.h

@@ -19,10 +19,9 @@ namespace H5 {
 
 /*! \class ObjCreatPropList
     \brief Class ObjCreatPropList inherits from PropList and provides
-    wrappers for the HDF5 file create property list.
-
-    Inheritance: PropList -> IdComponent
+    wrappers for the HDF5 object create property list.
 */
+//  Inheritance: PropList -> IdComponent
 class H5_DLLCPP ObjCreatPropList : public PropList {
    public:
         ///\brief Default object creation property list.