travis: split Android off OSX, use native image

cmd/abigen: parse contract name as abi identifier

closes #3650

event: use sync.Once for init for faster/cleaner locking

Signed-off-by: DiSiqueira <dieg0@live.com>

core/genesis: add support for setting nonce in 'alloc'

event: add new Subscription type and related utilities

event: address Feed review issues

event: clarify role of NewSubscription function

event: more Feed review fixes

* take sendLock after dropping f.mu
* add constant for number of special cases

event: fix subscribing/unsubscribing while Send is blocked

Reworked the EVM gas instructions to use 64bit integers rather than
arbitrary size big ints. All gas operations, be it additions,
multiplications or divisions, are checked and guarded against 64 bit
integer overflows.

In additon, most of the protocol paramaters in the params package have
been converted to uint64 and are now constants rather than variables.

* common/math: added overflow check ops
* core: vmenv, env renamed to evm
* eth, internal/ethapi, les: unmetered eth_call and cancel methods
* core/vm: implemented big.Int pool for evm instructions
* core/vm: unexported intPool methods & verification methods
* core/vm: added memoryGasCost overflow check and test

We must take a write lock here because `GetNonce` calls
`StateDB.GetStateObject`, which mutates the DB's live set.

les: fix private net issues, enable adding peers manually again

 cmd/swarm, swarm/api: bzzr improve + networkid prio

cmd/geth, cmd/swarm: Fix to close file handler appropriately

build: Fix tiny typo

fixes #3444
fixes #3494
networkid override

Added comments to explain why test against 0 appears twice

* Command line overrides saved config, saved config overrides system default

---

fixes #3476
bzzr get with path

Finally a hopefully clean commit for this PR
Added check for empty path to avoid SIGSEGV in path parser and resolver
Added requested tests for empty path and non-existing manifest.
However signature for StartHTTPServer had changed.
Now it's hacked as so:

	StartHttpServer(api.API, &Server{Addr: "127.0.0.1:8504", CorsString: ""})

* Parse url before resolve when path and ENS is supplied, example
* swarm/api/http proxy server test for retrieval of subpath through get
* Removed nil entry assignment on subtrie leaf in recursive key retrieval
* Cleaned up path-or-no-path condition in proxy server get handler
* swarm: processed with gofmt refers to lash/go-ethereum@90daa7a
* swarm: Added public access method Parse alias to parse
* swarm: processed with gofmt References nolash/go-ethereum@2ec3fd7
* Rename parse to Parse, removed alias

This change makes client subscriptions compatible with the new
Subscription semantics introduced in the previous commit.

This commit introduces a new Subscription type, which is synonymous with
ethereum.Subscription. It also adds a couple of utilities that make
working with Subscriptions easier. The mot complex utility is Feed, a
synchronisation device that implements broadcast subscriptions. Feed is
slightly faster than TypeMux and will replace uses of TypeMux across the
go-ethereum codebase in the future.