Soft-fork should only be primed to trigger if the gas-limit of
block #1760000 is at most 4,000,000.
To accomplish this we pass in the gas limit of that block to
EnvInfo so it can inform Schedule. This gets marshalled through
`OpenBlock`/`ClosedBlock` and the `enact` functions much like
`last_hashes`. `block.rs`'s `env_info()` takes care to ensure
that if the current block happens to be #1760000, then we
populate with the current `gas_limit`.
* refactor externalities::ret to take self by-value, add GasLeft enum, and alter evm::Result.
* remove unused imports, StopExecutionWithGasLeft variant
* adjust tests
* remove extraneous call to reserve
* update json_tests Ext to match new trait
* adjust executive json_test
* have evms own their memory for their entire lifetime
* make finalize API more friendly
* indentation fix
[ci skip]
* Groundwork for basic VM tracing.
* RPC endpoint for VM tracing and ser/de types ready.
* Create VMTracer trait.
* Rearchitected VM tracing to reflect existing tracing.
Should more or less work now.
* Integrated VM tracing into JSONRPC.
* Fix ethcore module tests.
* Add tests for VM tracing.
* Fix consensus test code.
* Fix mock tests.
* Added VM trace information for post-execution stuff.
* Fix max-value calls and add "creates" field to getTransaction.
* Tests for VM tracing.
* Don't implement the trait with unimplemented.
* Remove invlaid comment.
* Fix tests.
