It's not needed any more with Go 1.13 as we have wrapping/unwrapping in base
packages. All errors.Wrap calls are replaced with fmt.Errorf, some strings are
improved along the way.
In order to avoid dependency cycle at the next commits:
imports github.com/nspcc-dev/neo-go/pkg/config
imports github.com/nspcc-dev/neo-go/pkg/wallet
imports github.com/nspcc-dev/neo-go/pkg/vm
imports github.com/nspcc-dev/neo-go/pkg/smartcontract/nef
imports github.com/nspcc-dev/neo-go/pkg/config
part of #904
1. We now have MaxTransactionsPerBlock set in native Policy contract,
so this value should be used in (dbft).GetVerified method instead
of passing it as an argument.
2. Removed (dbft).WithTxPerBlock.
2. DBFT API has changed, so update it's version.
3. Removed MaxTransactionsPerBlock from node configuration, as we
have it set in native Policy contract.
There is no such thing as high/low priority transactions, as there are
no free transactions anymore and they are ordered by fees contained
in transaction itself.
Closes#1063.
