Set default handlers if they are not set (even if some other handlers are set).
Merge pull request #231 from aurimasv/defaultHandlers

Set default handlers if they are not set
Use Zotero.wait() to move progress indicator

This may help with #230
Only set timeout to 50 if undefined
Remove "Try to override conflicting shortcuts" pref

I probably should have removed this years ago in 292c357e when I made
the shortcut keys only work within the Zotero pane.
[Utilities] add cleanISSN
Allow translators to define translator-specific hidden preferences.
Tweaks to getHiddenPref()

- Remove references to configOptions, displayOptions, and hiddenPrefs
  from connector/translator.js. We can't rely on them to be set in
  Zotero.Translator since https://repo.zotero.org/repo/metadata doesn't
  provide them, but we shouldn't need them until we get the translator
  code anyway.
- Don't serve configOptions, displayOptions, and hiddenPrefs from Zotero
  Standalone server. There's no point in serving anything that
  https://repo.zotero.org/repo/metadata doesn't.
- Alias the translator metadata loaded into the sandbox as
  Zotero.Translate._translatorInfo. Use this to get configOptions and
  hiddenPrefs.
- "v" browserSupport indicates that a translator can be run through
  translation-server, not that translation-server is required.

This obviates the need for zotero/zotero-connectors#4.
Merge pull request #234 from aurimasv/cleanISSN

[Utilities] add cleanISSN
Update citeproc-js to 1.0.422
Tweaks to WebDAV preferences
[Zotero_TranslatorTester] Move _generateDiff  and _compare out of prototype
Consider type-specific "title" alternatives for validating web translations
Merge pull request #236 from aurimasv/generateDiff

[Zotero_TranslatorTester] Move _generateDiff  and _compare out of prototype
Better MIME type detection of Office files

For at least one Windows user, a .docx file was being interpreted as
text/plain. Instead of relying entirely on the system, hard-code some
extensions we know. (More can be added.)

Also:

- Determine MIME type when opening files instead of using stored type,
  since we might have gotten smarter
Use eraseByURI() instead of eraseByURIPrefix(), and fix params
Detect CAPTCHA
Merge pull request #235 from aurimasv/webdav

Tweaks to WebDAV preferences
Fall back to link attachments for opening item
Tweak patch from 41de387 to keep file style consistent