core: print import stats more often

core: lower transaction pool max queue limit

If geth is busy importing 2048 heavy blocks it can take a while before
it prints anything. This change ensures that a message gets printed
every 8s.

core/types: renamed receiptRoot to receiptsRoot

tests: update test files from github.com/ethereum/tests @ 45bc1d21d3c1

core/state: implement reverts by journaling all changes

Two new tests are skipped because they're buggy. Making some newer
random state tests work required implementing the 'compressed return
value encoding'.

There is no need to use the reflection-based decoder to decode []byte.

The delete/remove naming has caused endless confusion in the past.

This commit replaces the deep-copy based state revert mechanism with a
linear complexity journal. This commit also hides several internal
StateDB methods to limit the number of ways in which calling code can
use the journal incorrectly.

As usual consultation and bug fixes to the initial implementation were
provided by @karalabe, @obscuren and @Arachnid. Thank you!

eth: monitor malicious header retrieval requests

internal/ethapi: bugfix gas price and limit swapped in eth_resend

rpc: set CORS Max-Age to reduce preflight OPTIONS requests

internal/build: fix git tag env variable for AppVeyor

internal/build: use less edgy command to get the branch name

core/state: track dirty state entries for each object

build: improve debian packaging

This commit tweaks the debian packaging tool:

* All build environment metadata can now be overriden on the command
  line. This allows testing the CI build behaviour locally.
* -unstable packages now actually contain the binaries (oops)
* packages use Go 1.7 to build
* archiving is skipped for PR builds

crypto/sha3: update from golang.org/x/crypto/sha3 a 80b25ed4

This pulls in the assembly implementation of keccakf1600 for amd64.

cmd, core, internal, light, tests: avoid hashing the code in the VM

trie: fix delete bug for values contained in fullNode

accounts: left pad keybytes-to-encrypt

Delete crashed if a fullNode contained a valueNode directly. This bug is
very unlikely to occur with SecureTrie, but can happen with regular
tries. This commit also introduces a randomised test which triggers all
trie operations, which should prevent such bugs in the future.

Credit for finding this bug goes to Github user @rjl493456442.

Package crypto needs cgo, which is inconvenient for some build
configurations.

cmd/utils, node: make datadir reusable for bzzd

README: Changed http:// to https:// on some links

core, trie: replace state caches with trie journal