Fix cleanISSN
Closes #397, Support authenticated PAC setups in Standalone

Trigger a proxy authentication prompt at startup if a PAC file is
installed and one of a few randomly chosen big sites requires a proxy.

This also improves general proxy detection by not making a request
to S3 unless it would actually be proxied.
Read 200 bytes instead of 128 in Zotero.File.getSample()

This allows Zotero to detect PDFs with more gibberish at the beginning.

https://forums.zotero.org/discussion/32550
Fix "Open Documentation" button in WebDAV verification cert error dialog
add report to COinS export and add some import support
Tweaks to #384

- Prefer btitle to title for OpenURL 1.0
- Remove unnecessary institution mapping (base-field mapped to publisher)
- Formatting fixes
Merge pull request #396 from aurimasv/cleanISSN

Fix cleanISSN
Merge branch '4.0' of https://github.com/zotero/zotero into multi-4.0-dev