Installer regression from dd49834
BUG Fixed incorrect CSS class on MoneyField holder
BUG Fixes serious issue with FieldList::addFieldsToTab failing to accept multiple field groups.

Additional groups beyond the first are ignored.
Test cases included.
FIX oembed to avoid mixed media issues
Merge pull request #2556 from tractorcow/pulls/3.1-bug-fieldgroup-name-fix

BUG Fixes serious issue with FieldList::addFieldsToTab failing to accept multiple field groups.
Merge pull request #2554 from tractorcow/pulls/3.1-moneyfield-style-fix

BUG Fixed incorrect CSS class on MoneyField holder
FIX Changing `public` static `$priority` to `private`

Deprecation error thrown in master whilst this is public
Merge pull request #2539 from dhensby/patch-2

FIX Changing `public` statics to `private`
BUG Less misuse of error control operator (@)
This is necessary to prevent get_last_error() from returning suppressed errors when retrieving values from nested arrays
Merge pull request #2545 from hafriedlander/fix/protocol_and_oembed

FIX oembed to avoid mixed media issues
Merge pull request #2563 from tractorcow/pulls/3.1-error-control-usage

BUG Less misuse of error control operator (@)
Merge remote-tracking branch 'origin/3.0' into 3.1
Using Behat EmailContext by default