mapgen: added halo effect around papers to indicate arxiv category.
mapgen: added halo effect around papers to indicate arxiv category.

paperscape/paperscape-mapgen,paperscape/paperscape-mapgen,paperscape/paperscape-backend,paperscape/paperscape-backend,paperscape/paperscape-backend,paperscape/paperscape-backend,paperscape/paperscape-mapgen,paperscape/paperscape-mapgen