More generic handling of PublicationXref

[jvwong]

It is not safe to assume that a PublicationXref originates from PubMed, as we have done. Article references from elsewhere would break the existing logic:

app-ui/src/client/features/interactions/interactions-edge-tooltip.js

Lines 73 to 79 in b28e1e6

	let publicationList = publications.map( publication => {
	let { id, title, firstAuthor, date, source } = publication;
	return h('div.cy-overflow-content', [
	h('a.plain-link', { href: 'http://identifiers.org/pubmed/' + id, target: '_blank' }, title),
	h('div', firstAuthor + ' et al. | ' + source + ' - ' + new Date(date).getFullYear().toString())
	]);
	});

In this case, it also makes sense to utilize available information about an article, so that the system need not make additional calls or support an external web service to retrieve it (e.g. crossref).

Related to: PathwayCommons/factoid#1218

[jvwong]

At this point, references to an article are through PubMed and is baked into EXTENDED_BINARY_SIF. So there will need to be some design changes to the source x-SIF data....