Upgrade to combine 4.x.y

[DoumanAsh]

Subj
Most notable change is combine::parser doesn't accept functions that return combine::ParseResult so you have to convert it each time.
Probably could just write own version that accepts combine::ParseResult to avoid conversion

[tailhook]

Hi! Thanks for the PR. And sorry for late reply. There are two issues with the PR.

1. unexpected_format should probably be replaced by unexpected_static_message instead where message in static (pretty minor)
2. Instead of parse_stream(input).into(), I think we should use -> impl Parser<..> return everywhere (there was no -> impl at the point this was originally implemented, this is why it's not used). The change should be pretty mechanical, although we need to use opaque! macro at some place where nested nodes are used.

[DoumanAsh]

Got it
Although it doesn't seem to me that replacing parser functions with just returning impl Parser is all that simple to be honest.
But then again I'm not all that familiar with combine

[LegNeato]

This has been superceded.