Handling Literals

[jbkoh]

Literals are individually instantiated per triple regardless of their values. Though their values can be the same, different Literals should be visualized as individual nodes in the graph. However, the current frontend logic regards everything with its name (i.e., identifier), the Literals with the same value are actually modeled as a single node.

@shreyasnagare Please take a look at this when you find time. Thanks!