Linter isn't happy with our recent changes:
pkg/core/contract_state.go:109:1: receiver name cs should be consistent with previous receiver name a for ContractState
pkg/core/contract_state.go:114:1: receiver name cs should be consistent with previous receiver name a for ContractState
pkg/core/contract_state.go:119:1: receiver name cs should be consistent with previous receiver name a for ContractState
But actually `a` here most probably is a copy-paste from AssetState methods,
so fit the old code to match the new one.
PublishTX only had one of these flags, but newer contracts (created via the
interop function) can have more and these flags are aggregated into one field
that uses PropertyState enumeration (it's used to publish contract, so
supposedly it's also a nice choice for contract state storage).
