Updated and collated plugins for vis-network library

Thanks to @linonetwo for introducing my vis-network plugin. This just fills it out more. And also gets rid of the old visjs plugin, which nobody should be using. It's bigger. It's not maintained. It doesn't work with TW5-Graph. Having it in CPL will only confuse people trying to use TW5-Graph or Tiddlymap. In turn, I'm giving Felix Küppers an author credit on the vis-network plugin, since he did make the basis of the code that the plugin uses. Also, updating some links so that everyone finds the correct plugin dependency.