use snapshot for ED/EDT validation

[ixje]

What current issue(s) does this address, or what feature is it adding?
audit of testnet block 2842737 showed a deviation in VM state due to not using snapshots for CALL_ED/EDT dynamic invoke validation. This should have been part of #995

How did you solve this problem?
use same logic as #995

How did you make sure your solution works?
audit of block passes

Are there any special changes in the code that we should be aware of?

Please check the following, if applicable:

• Did you add any tests?
• Did you run make lint?
• Did you run make test?
• Are you making a PR to a feature branch or development rather than master?
• Did you add an entry to CHANGELOG.rst? (if not, please do)

[coveralls]

Coverage decreased (-0.004%) to 85.263% when pulling 73f73ab on ixje:check-dynamic-2 into a7993c2 on CityOfZion:development.