AIP #61 v5: NewState and Accounting

[elpiel]

Sentry

NewState and Accounting should contain 2 balances maps (for earners and spenders) and we need to be able to distinguish between them:

• balances - earners map
• balancesSpenders - spenders map

IMPORTANT: Although there is division in 2 maps of the balances, the state_root should contain both (i.e. the should be merged into a single tree)

balancesSpenders - in order to avoid duplication when merging the two maps, spenderLeafs should be hashed by hash("spender", spender, totalSpent) (notice the string slice included when hashing to create a different hash than the earners map)

Accounting:

• Used to create NewState & ApproveState V5 validator workflow - Follower & Leader ticks #428
• Filled by the flat sentry::db::Accounting for a given Channel Issue 431 get accounting for channel #439
• MerkleTree should use actual precision of the token (e.g. DAI - 18, USDT - 6, etc.) Preparations for V5 validator workflow #426