crypto/secp256k1: remove dependency on libgmp

core: added a new RemovedLogEvent

Turns out we actually don't need it, USE_NUM_NONE works
because we also set USE_FIELD_INV_BUILTIN.

Makefile: support 64bit ARM iOS cross builds

Makefile: enable 64-bit ARM builds on Linux

crypto, crypto/secp256k1: use libsecp256k1 for scalar multiplication

accounts: increase re-lock timeout to account for slow CI servers

Makefile: build ARM v5/v6/v7, drop high API mobile clients

Trie error handling

cmd/utils: restore starting geth without any accounts and etherbase

When a chain reorganisation occurs we collect the logs that were deleted
during the chain reorganisation. The removed logs are posted to the
event mux indicating that those were deleted during the reorg.

Also remove some duplication around address/index parsing.

eth package creates new event mux

Created alternate versions of Trie and SecureTrie functions that can return a MissingNodeError (used by ODR services)

console: fix instance name printed incorrect on start

thanks to Felix Lange (fjl) for help with design & impl

Makefile: enable iOS experimental builds (fix prev omission)

common: fix #2008, wrong hex prefix check

Customizable protocol stacks

Makefile: add support for iOS cross compilation

jrse: fix #1082, fail if setTimeout/setInterval lack callback

cmd, crypto: updated web3

whisper: fixed broadcast race

Whisper's expire and broadcast loops happen in two separate go routines.
Whenever an envelope is being expired it's removed from the set of
envelopes and it looses all information about the envelope, including
the "known hash". After the envelope has been removed it can be
re-accepted by a broadcasting peer putting back the envelope in the set
of envelopes. Since the envelope broadcast loop is separate of the
expire loop expired messages may be broadcast to other peer, resulting
in messages **never** being dropped.

This PR includes an expire check before adding new messages to the set
of envelopes.