Hoisting Private Key & Mnemonic Accounts to top level config.

[versedpro]

Hello folk,

I'd recommend including private key settings in the config so that developers can leverage this feature everywhere without having to explicitly specify it.
I'm working on a crypto-finance 3rd party application that allows a trusted user to manage something on behalf of someone else (like a decentralized trading bot or an agent for someone else). Passing an account to every action in this case is a pain in the neck of code optimization and can cause some vulnerabilities in my opinion.
Looking forward to the next version update.

Thanks in advance.