* accounts: add note about backing up the keystore
* cmd, accounts: move the printout to accountCreate
* internal, signer: add info when new account is created via rpc
* cmd, internal, signer: split logs
* cmd/geth: make account new output a bit more verbose
* cmd, consensus, core, miner: instatx clique for --dev
* cmd, consensus, clique: support configurable --dev block times
* cmd, core: allow --dev to use persistent storage too
In order to avoid disk thrashing for Accounts and HasAccount,
address->key file mappings are now cached in memory. This makes it no
longer necessary to keep the key address in the file name. The address
of each key is derived from file content instead.
There are minor user-visible changes:
- "geth account list" now reports key file paths alongside the address.
- If multiple keys are present for an address, unlocking by address is
not possible. Users are directed to remove the duplicate files
instead. Unlocking by index is still possible.
- Key files are overwritten written in place when updating the password.
