Refs #2320: “Vizmap XML files” replaced by "Style XML files” on the Export Style dialog.
Refs #2320: Using DataCategory.getDisplayName() instead of toString().
Tasks window is now centered on Cytoscape desktop frame
Merge branch 'release/3.1.0' of https://github.com/cytoscape/cytoscape-impl into release/3.1.0
Fixed broken d3 exporter.