';' can not be used to separate emails in Cc field

Semicolon is used to end a group if there is a group, but
can not be used to separate emails without group.
change how we deal with decoding structured fields

When we get rid of encoded words in formatted fields (From/To/Cc,
Content-Disposition, Content-Type...), we have to take care of
preserving structure of the field which means quoting parts. Old code
were using luck and magic to achieve this instead of parsing field's
structure.

We use MIME::Field::ParamVal already to deal with continued params
(RFC2231). This module allows us to deal with separate parameters,
decode them and deal with quotes inside or absence of those without
guessing.

Bump the version to a version which fixes a bug [1] in parsing of quoted
strings and quoting on stringify.

Similar situation with From, Cc, Bcc and other fields with mailboxes. We
were only dealing with subset of mailbox fields, now we handle all such
headers that are mentioned in RFC5322.

Switch to Email::Address::List to parse headers with mailboxes. Allows
us to report errors, handles obsolete emails, don't bails out on not
ascii.

Email::Address is still used and a bug [2] was discovered in the module
that may result in unparsable string after re-composing.

[1] https://rt.cpan.org/Ticket/Display.html?id=80433
[2] https://rt.cpan.org/Ticket/Display.html?id=81170
deal with hidden quotes within encoded-word

After decoding a part (a param value or display name)
may contain a quoted string inside, we de-quote and
de-escape it just to avoid useless quotes.
test more MIME word decoding cases
Tests: Adjust diagnostic descriptions to match what's actually being tested
Tests: Correct a typo'd email address in the From: header
Tests: Catch the new "unparseable email address" warnings

A warning is now issued for each header field instead of a single
warning for all sender fields.
Tests: Remove Requestors from approval templates

The ->Requestors method returns an RT::Group object which stringified
during template interpolation.  The new email address parsing balks at
RT::Group=HASH(0xDEADBEEF), appropriately so.  Providing the actual
requestor email addresses would cause autoreplies to go out and the rest
of the test assumptions to break, so simply remove the requestors all
together.  Generally approval tickets don't use requestors in real use
cases anyway.
Tests: Catch warnings when calling DecodeMIMEWordsTo* without a field name

Or provide a field name when possible to avoid the warnings altogether.
We explicitly test without field names to compare results, but no where
in core RT should do the same.
Tests: Set a correspond address

... so we don't try to parse an empty address on the way back in.
Tests: Double quotes are not allowed by our email address parsing

The double quote case for requestor email addresses is skipped further
down in the file, but the ticket was still created with a bogus
requestor.  Avoid the added warnings by skipping the requestor when
testing double quotes.
Remove assumptions that we might have Email::Address < 1.897
Merge branch '4.2-on-4.0/protect-more-chars-while-decoding-headers'

Conflicts:
	lib/RT/I18N.pm
	sbin/rt-test-dependencies.in

t/web/scrips.t failed due to stricter parsing of email addresses when
forwarding, and was adjusted to provide an email address with a domain.