* fixed leak of cached metadata and sil. delete the cached
  data before clear'ing the container.

* make copy constructor and assignment operator private since
  using the default implmentations would result in multiple
  delete's of raw pointers held stl containers. make names of
  variables used to limit cache sizes describe their purpose.

* cleanup warnings from this class reported by -Wall



git-svn-id: http://visit.ilight.com/svn/visit/trunk/src@23230 18c085ea-50e0-402c-830e-de6fd14e8384