Merge pull request ethereum#489 from ethereum/retestethcfg

retesteth client configs [WIP]

Merge pull request ethereum#544 from ajsutton/extcodehash

Add EXTCODEHASH tests

Merge pull request ethereum#533 from ethereum/blockchain-test-format-…

…doc-updates

Blockchain test format doc updates on seal engine type

fix tests for invalid uncle difficulty

All tests are compatible