option to use external (to geth) private keys for signing tx's

[wanderer]

It might be nice to have an option to use external keys for signing the tx's

[axic]

It is on my todo list. I would need to move on to web3-provider-engine first. Actually I was considering creating a sort of web3-cli module which makes it easier to use in a commandline environment (as opposed to the web3), i.e. it would define a configuration file in the home directory, etc.