Local origination of several contracts when using the "run script" command

When using the run script command a dummy contract is locally originated at the address that SELF returns during the origination so both BALANCE and SELF; ADDRESS; CONTRACT; ASSERT_SOME always succeed as they should. By "locally originated" I mean that the context containing the originated contract does not survive the simulation.

This feature request is about extending this mechanism to allow local origination of more contracts prior to simulation; it is being requested by Michael Zaikin (from Baking Bad). The applications are integration tests of Michelson contracts and off-chain calls to views (implemented using callbacks).

A similar feature exists for the TZT format (see nomadic-labs/tezos#63).