This PR exploits structural properties of era files to simplify the
implementation and in particular remove the need to load all era file
indicies at startup which may be slow (due to archival storage residing
on slow drives)
* Update some docu & messages
* Remove cruft from the ledger modules
* Must not overwrite genesis data on an initialised database
why:
This will overwrite the global state of the Aristo single state DB.
Otherwise resuming at the last synced state becomes impossible.
* Provide latest block number from journal
why:
This relates the global state of the DB directly to the corresponding
block number.
* Implemented unit test providing DB pre-load and resume
Jacek Sieka
Jordan Hrycaj