This is mostly for automated tests. The tests can use the following
commands to start the node:
ethereum --unencrypted-keys account new
...
ethereum --unencrypted-keys
The ethereum command line interface is now structured using subcommands.
These separate the different tasks it can perform.
Almost all flag names are backwards compatible.
The key tasks have not been ported to subcommands since they will be
replaced by the new accounts infrastructure very soon.