NextBlockValidators are updated before the new block persist, so we need to
use GetValidators to get the list corresponding to the current state of the
chain.
Even if the value is zero, the GAS distribution updates the balance height, so
storage item must be updated too. Fixes the followin on preview2 testnet:
block 74227: value mismatch for key ffffffff1454a6cb279fbcedc66162ad4ad5d1d910202b92743e000000000000000000000005: 1041032104809fd5002103f3210128010000 vs 1041032104809fd50021033f110128010000
They make no sense. Fixes preview2 testnet state problem:
file BlockStorage_100000/dump-block-70000.json: block 69935: state mismatch for key ffffffff1454a6cb279fbcedc66162ad4ad5d1d910202b92743e000000000000000000000005: Deleted vs Added
ValidatorsCount is not initialized at block 0 with C# node (the first voter
initializes it) and until that initialization happens the standby validators
list is being returned as is without sorting.
Fixes state mismatch for the key ffffffff0e00000000000000000000000000000001 in
the first blocks.
It also affects tests as now the first validator is different and it receives
the network fees.
`NewNEO()` and `NewGAS()` methods are trying to initialise
both `onPersist` and `incBalance` methods of NEO and GAS AFTER
nep5TokenNative is set to the VALUE of created nep5 token.
In this situation an attemmpt to call the corresponding native contracts
methods (e.g. transfer native GAS) leads to contract invocation failure,
as far as `nep5TokenNative.incBalance` method is nil.
Fixed this by initializing both `onPersist` and `incBalance` methods
before getting the value of nep5 contract.
The notion of NativeContractState shouldn't ever existed, native contract is a
contract and its state is saved as regular contract state which is critical
because we'll have MPT calculations over this state soon.
Initial minting should be done in Neo.Native.Deploy because it generates
notification that should have proper transaction context.
RegisterNative() shouldn't exist as a public method, native contracts are only
registered at block 0 and they can do it internally, no outside user should be
able to mess with it.
Move some structures from `native` package to `interop` also to avoid circular
references as interop.Context has to have a list of native contracts (exposing
them via Blockchainer is again too dangerous, it's too powerful tool).
