Context keys must have a unique type in order to prevent
any unintented clashes. The code used int(1) as key.

Fix it by implementing the pattern recommended by package context.

all: fix go vet warnings

whisper: deflake Test*MessageExpiration

These tests have become a common annoyance on CI. Fix them by allowing
messages with expiration == now into the cache and delaying the check
for expired message handling slightly.

Lazy "I'll just put return here instead of fixing the test" found by go vet.

logging.printf triggered a format string warning. Silence it
by renaming the function.

This fixes a few uses of unkeyed Body literals which go vet was
complaining about.

all: update license information

cmd/utils: strip excessive whitespace from api command line arguments

eth: fix single transaction tracing (run prev mutations)

eth: add chaindbProperty to debug API (+ console fixes)

This makes web3 internals like _requestManager invisible.

accounts: disable filesystem notifications on iOS

jsre: print BigNumber objects with custom constructor as number

cmd/utils: fix accounts merge error on console unlock

accounts: cache key addresses

cmd/gethrpctest: add missing chain configuration config field

- Sign takes common.Address, not Account
- Import/Export methods work with encrypted JSON keys

Text files created on Windows typically have \r\n line endings.
Trim them when reading password files.

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.