Optimising JS visualisation for notebooks

In a large number of notebooks that are created and used by users of CERN, many important components are those related to graphical visualization. These include, but are not limited to graphs and histograms of data and events from physical detectors. However, the information used to display the ROOT graphical primitives is too comprehensive and hence cause the physical space requirements of the notebooks to grow drastically as the number of graphs and plots increases. Analysis has been performed to trim out redundant information from the notebooks, as well as providing insight into browsing ROOT objects within a notebook.