Make sure the costs are correct for re-entrant calls

[abizjak]

Task description

We have changed/fixed the semantics of re-entrant calls in the node in P6.

We should make sure that the costs in the testing library are correct. In particular

• add the re-entrant tests from the node to the tests of the library
• make sure that the library reports correct cost
• make sure the library then also reports correct "state has changed" back to the contract.