This PR refactors the eth test suite to make it more readable and
easier to use. Some notable differences:
- A new file helpers.go stores all of the methods used between
both eth66 and eth65 and below tests, as well as methods shared
among many test functions.
- suite.go now contains all of the test functions for both eth65
tests and eth66 tests.
- The utesting.T object doesn't get passed through to other helper methods,
but is instead only used within the scope of the test function,
whereas helper methods return errors, so only the test function
itself can fatal out in the case of an error.
- The full test suite now only takes 13.5 seconds to run.
The old one was wrong in two ways: the first block in chain.rlp was the
genesis block, and the genesis difficulty was below minimum difficulty.
This also contains some other fixes to the test.
