It is now possible to exit the REPL using Ctrl-C, Ctrl-D or by typing "exit".

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.

Various functions throughout the codebase used it to grab settings. This
has to stop because I want to use them without reading the config file.

These functions can now be used without reading the config first:

* ethdb.NewLDBDatabase
* ethrepl.NewJSRepl
* vm.New

* Added an additional tx state which is used to get the current nonce
* Refresh transient state each time a new canonical block is found
* Properly uninstall filters. Fixes a possible crash in RPC

* Implemented `eth_logs`
* Fixed issue with `filter.Find()` where logs were appended to an
  incorrect, non-returned slice resulting in no logs found

Defaults to the amount of cores available on the CPU

also fixed an issue where it would force reloads unnecessarily