message::parse_many_ids() fails to parse ID lists without spaces

[tsilia]

Hello.
I have run into an issue: message::parse_many_ids() can't parse ID strings which don't contain a space separator, like this one:
<029601d56c86$60e6e5e0$22b4b1a0$@mail.ru><02d901d56c96$89591ab0$9c0b5010$@mail.ru><114a0364-0ff7-f9ca-942a-3f58e45be343@otherdomain.tld>

It's a great library which implements almost all features I need, but right now it's not possible for me to fetch some e-mails due to an exception thrown: Parsing failure of the message ID. Thunderbird fetches such messages successfully.

Please, is there anything you could do to support such space-lacking ID lists as this seems to be a common misbehaviour of mail servers?

I've read another issue (#7) and saw you mentioned 'strict' mode which can be turned off to lift some restrictions. I did so and it didn't resolve the issue. I guess, this doesn't apply to parsing ID lists. Could you please extend the non-strict mode to ID lists?
Thank you.

[karastojko]

RFC 5322 section claims that IDs may be separated by one or more whitespaces. Thus, there is no need for the strict mode in this case, it has to work always. Check the PR55.