Review: Total Ring/Kton Range

[aurexav]

Relate to #267.

/// A structure to demonstrate the phragmen result from the perspective of the candidate, i.e. how
/// much support each candidate is receiving.
///
/// This complements the [`PhragmenResult`] and is needed to run the equalize post-processing.
///
/// This, at the current version, resembles the `Exposure` defined in the staking SRML module, yet
/// they do not necessarily have to be the same.
#[derive(Default, RuntimeDebug)]
#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize))]
pub struct Support<AccountId, RingBalance, KtonBalance> {
	/// The amount of support as the effect of self-vote.
	pub own_votes: Votes,
	pub own_ring: RingBalance,
	pub own_kton: KtonBalance,
	/// Total support.
	pub total: Votes,
	pub total_ring: RingBalance,
	pub total_kton: KtonBalance,
	/// Support from voters.
	pub others: Vec<PhragmenStakedAssignment<AccountId, RingBalance, KtonBalance>>,
}

Total Ring is around 10_000_000_000 * 10^9.
Total Kton won't grow too large in real world.

So I presume:

let total_ring/kton = own_ring/kton + others.iter().sum();
assert!(total_ring/kton < u128::max_value());