More robust slash-unescaping for JabRef group import, cleanup, handles JabRef group intersaction

Although it handles the intersections by making them static.
make EBSCO work in discovery layers, even in guest mode. Replaces https://github.com/zotero/translators/pull/598
[Primo] Favor Details link. Improve PNX detection
add a sici? to JSTOR target regex for referal links from WoS
[zotero.org] Monitor DOM changes and use correct xpaths.
[zotero.org] Don't include attachments in multiples.
Also remove monitorDOMChanges.
remove DESCRIPTOR tag in RIS which is redundant and invalid/breaks our RIS type detection. Update tests for keyword format change
[EM] Look for prefix definitions in html and head "prefix" attributes
[EM] Allow multiple predicates inside name/property attribute
small fixes to CanLII, Zeit, Epicurious, Foreign Affairs
small Google Books & Patents fixes
large repair on OSTI. Be more picky about TOCs for IoP, test update for IPAP
also attach dissertation (and other?) previews
a bunch of small fixes
more small fixes or test updates
HuffPo dates, ProjectMuse clean up abstracts
[NPG] Try to compensate for authors that are missing from EM data
Closes #625
Merge branch 'master' of git://github.com/zotero/translators
fix slate after site update
small fixes to Roll Call, Toronto Star; adapt to site redesign for SAE