near-runtime-fees

Fees applied to near runtime encapsulated in a separate crate. Might merge it later.

lib.rs:

Describes the various costs incurred by creating receipts. We use the following abbreviation for readability:

• sir -- sender is receiver. Receipts that are directed by an account to itself are guaranteed to not be cross-shard which is cheaper than cross-shard. Conversely, when sender is not a receiver it might or might not be a cross-shard communication.