Use `in_place` suffix for `BigInteger` operations

[tcoratger]

In the whole codebase, there is a standard which is to include the suffix in_place on operations which modify the value passed as a mutable parameter. For example here:

algebra/ec/src/models/bn/g2.rs

Lines 53 to 77 in cc2ad8c

	fn double_in_place(&mut self, two_inv: &P::Fp) -> EllCoeff<P> {
	// Formula for line function when working with
	// homogeneous projective coordinates.
	let mut a = self.x * &self.y;
	a.mul_assign_by_fp(two_inv);
	let b = self.y.square();
	let c = self.z.square();
	let e = P::G2Config::COEFF_B * &(c.double() + &c);
	let f = e.double() + &e;
	let mut g = b + &f;
	g.mul_assign_by_fp(two_inv);
	let h = (self.y + &self.z).square() - &(b + &c);
	let i = e - &b;
	let j = self.x.square();
	let e_square = e.square();
	self.x = a * &(b - &f);
	self.y = g.square() - &(e_square.double() + &e_square);
	self.z = b * &h;
	match P::TWIST_TYPE {
	TwistType::M => (i, j.double() + &j, -h),
	TwistType::D => (-h, j.double() + &j, i),
	}
	}

We know from the function name that the self mutable will be modified.

However similar operations are performed in the BigInteger trait like:

algebra/ff/src/biginteger/mod.rs

Line 1062 in cc2ad8c

fn mul2(&mut self) -> bool;

or

algebra/ff/src/biginteger/mod.rs

Line 1037 in cc2ad8c

fn sub_with_borrow(&mut self, other: &Self) -> bool;

without including the in_place suffix. For readability and consistency, it could be nice to include this suffix for all the BigInteger operations concerned by this type of logic.

[Pratyush]

Yes, this would be great!