Disallow transfering tz from a contract
Clarification and motivation
Michelson.Runtime
allows transferring tz from an implicit account and from a contract, whereas the reference implementation only allows transferring tz from an implicit account (and not from a contract)
We should make sure this is not possible in Michelson.Runtime
either.
Acceptance criteria
If we have a nettest that transfer tz from a contract, that test should fail on both the emulator and on a real network.