* Initial implementation of era1 + export + verify
Initial implementation of era1 + export and verify command in the
existing eth_data_exporter.
* Quick verify version to test with geth created era1 files
* Add Era1File object and getter for specific block tuple
* Add getAccumulatorRoot and update AccumulatorRoot type name
+ clean-up of some comments.
* Implement BlockIndex based verify + additional helper calls
+ fix bug for reading last (incomplete) Era1 file
* Fix init BlockIndex offsets for last era + extra check on reading
* Remove duplicated e2store code
* Reduce Nim 1.6 compiler warnings/hints for Fluffy and Nimbus proxy
Mostly raises Defect removals, TaintedString removal and some
unnecessary imports.
Also updating the copyright years alongside.
* Further reduce Nim 1.6 compiler warnings/hints for Nimbus
Kim De Mey