Pseduo-remove MapToCurve::new, renamed to check_parameters

[burdges]

Description

MapToCurve::new seemingly originates from a more runtime oriented elliptic curve crate: https://github.com/armfazh/redox-ecc/blob/master/src/ellipticcurve.rs#L36

Arguably test_parameters should be inherent methods, invoked by whoever defined the parameters, but maybe not? I left the trait method for now. I suspect the hash-to-curve code would benefit form a wider more idiomatic rewrite btw.

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[mmagician]

Looks good. @burdges Can you merge latest arkworks master into your branch pls? I can't do it since the PR came from an org

[burdges]

Appears @weikengchen did so, no idea how these rules all work.

Just fyi, I've a larger successor master...w3f:arkworks-algebra:xof_h2c approaching readiness, which answers #629 and #630.

[mmagician]

Seems that the previous merge introduced some conflicts. Maybe that's a good chance for @burdges to add a line to the CHANGELOG :)

[Pratyush]

I have one question @burdges: the current approach ensures that one can't construct an invalid map and use it, while the new code allow using an invalid mapping. Do you think there's an easy way to preserve the old behaviour?

[burdges]

Do you think there's an easy way to preserve the old behaviour?

It could be invoked behind #[cfg(debug_assertions)] further up the stack: https://github.com/arkworks-rs/algebra/compare/master...w3f:arkworks-algebra:xof_h2c?expand=1#diff-d4ed998b41839f70c99ab6471a8c55b448ae708642d0a8e87f826e4b071e79f8R54

I sucked this up into #643 too. I could not parse @mmagician comment but likely it's done there too.

[burdges]

I'll close this in favor of #679 which is basically identical, but permits edits by maintainers