* Add signed refund
* Use signed 256-bit integer for sstore gas refund substate
* Fix tests
* Remove signed mod and use i128 directly
* Fix evm test case casting
* Fix jsontests ext signature
* Add new Vm trappable interface
* Exec/Resume interface
* Basic implementation of CallCreateExecutive
* Implement resume_call and resume_create for executive
* Move convertion to call/create result to separate function
* Implement consume that converts resumable to non-resumable
* Use consume for Executive::call/create
* Resumable EVM
* Implement tracing mode without needing subtracers
* Implement vmtracer so it doesn't require extra structs for subtracing
* Use the new tracing mode in executive
* Fix most of the linting errors for cargo build
* Add the concept of stack_depth
* Add back crossbeam
* Fix some test compile
* Fix prefix address test
* Fix evm crate tests
* Fix wasm crate test compile
* Fix wasm runner compile
* Fix jsontests compile
* Fix evmbin compile
* Fix an issue with create nonce and better vm tracing interface
* Fix linting
* Fix evmbin compile
* Fix unconfirmed_substate and static_flag
* Fix an issue in create address logic
* Fix top-level tracing
* Handle builtin tracing
* Fix suicide and reward tracing index stack
* Fix an issue where trap conflicts with tracing
* Fix an issue in parent step vm tracing
* Fix revert tracing
* Fix evmbin tests
* Remove params clone
* Fix TODO proofs
* Fix jsontests compile
* Fix evmbin merge issue
* Fix wasm merge issue
* Fix wasm test
* Fix ethcore merge warnings
* Fix evmbin compile
* Better expect messages and add some trace::skip_one asserts
* Implement last_checkpoint_storage_at
* Add reverted_storage_at for externalities
* sstore_clears_count -> sstore_clears_refund
* Implement eip1283 for evm
* Add eip1283Transition params
* evm: fix tests
* jsontests: fix test
* Return checkpoint index when creating
* Comply with spec Version II
* Fix docs
* Fix jsontests feature compile
* Address grumbles
* Fix no-checkpoint-entry case
* Remove unnecessary expect
* Add test for State::checkpoint_storage_at
* Add executive level test for eip1283
* Hard-code transaction_checkpoint_index to 0
* Fix jsontests
* Add tests for checkpoint discard/revert
* Require checkpoint to be empty for kill_account and commit
* Get code coverage
* Use saturating_add/saturating_sub
* Fix issues in insert_cache
* Clear the state again
* Fix original_storage_at
* Early return for empty RLP trie storage
* Update comments
* Fix borrow_mut issue
* Simplify checkpoint_storage_at if branches
* Better commenting for gas handling code
* Address naming grumbles
* More tests
* Fix an issue in overwrite_with
* Add another test
* Fix comment
* Remove unnecessary bracket
* Move orig to inner if
* Remove test coverage for this PR
* Add tests for executive original value
* Add warn! for an unreachable cause
* Remove pass-by-reference return data value from executive
* Fix tests
* Fix a missing test output
* typo: wasm_activation_test
* Tracing change in output
* json_tests: fix compile
* typo: 0..32 -> ..32 to keep it consistent with other occurance
* Fix tests
