Make Montgomery parameters public

[frozenspider]

Please make fields inside MontyParams (at least via getters) and mod_neg_inv function public. I don't think there's a real reason to hide them, and that prevents implementing custom algorithms like optimized multiplication.

[tarcieri]

Please be specific about what you want. mod_neg_inv? modulus is public:

https://docs.rs/crypto-bigint/latest/crypto_bigint/modular/struct.MontyParams.html

What else do you want and why? What exactly are you implementing?

[frozenspider]

Also having access to mod_inv itself would be nice.
I tried to implement an optimized multiplication that seems to work faster on my machine: https://gist.github.com/frozenspider/3f2846df339314efdd81a1995ba1df56 for the crypto-primitives repo. But I would also like to expose these values from my wrappers without having to waste time/memory recomputing them.

[tarcieri]

Feel free to open a PR adding accessor methods for the parameters you need