les, les/flowcontrol: implement LES/3

* Update codeowners

* Add karalabe to clique

* remove codeowner for consensus/clique

* Removed comment section referring to Cloudflare's bn curve parameters

* Added comment to clarify the nature of the parameters

* Changed value of xi to i+9

internal/build: fix Travis and AppVeyor commit string injection

vendor: update go-duktape to v2.3.0

accounts/scwallet: Display PUK retry count

* core: reinit chain from freezer in batches

* core/rawdb: concurrent database reinit from freezer dump

* core/rawdb: reinit from freezer in sequential order

Without this, accounts/keystore fails to build for Darwin with
CGO_ENABLED=0.

core/rawdb: keep genesis in key-value store for full sync too

* eth, les: reject light client connection is server is not synced

* eth, les: rename function and variables

* les: format

* p2p: remove direct import of cgo-library

* accounts, rpc: more nocgo alternatives

* rpc: move unix path constant into separate file

* accounts/scwallet: address review concerns, remove copy-pasta

* Added checks for nil pointers in Marshal functions

* Set nil pointer to identity in GT before marshaling

* tests: make transaction tests run again, fix #19033

* tests: refactor transaction tests

* log: Do not pad too long values

* log: gofmt

* les: avoid fetcher deadlock on requestChn

core/rawdb, eth/downloader: align 64bit atomic fields

* build: disable swarm packages

* build: remove allCrossCompiledArchiveFiles; inline allToolsArchiveFiles

* build: get rid of some superfluous comments

cmd, core, eth, les, node: chain freezer on top of db rework

* swarm/network: bump network id for 0.4 release

* swarm/network: bump bzz protocol version

* swarm/docs: migration document v0.3 to v0.4

* swarm/storage/feed: gofmt lookup_test.go