replace tabs by spaces in the code owners file

Access count was not incremented when chunk was retrieved
from cache. So the garbage collector might have deleted the most
frequently accessed chunk from disk.
Co-authored-by: Ferenc Szabo <ferenc.szabo@ethereum.org>

* p2p/simulations: Add custom services to simnodes + remove sim down conn objs

* p2p/simulation, swarm/network: Add selective services to discovery sim

* p2p/simulations, swarm/network: Remove useless comments

* p2p/simulations, swarm/network: Clean up mess from rebase

* p2p/simulation: Add sleep to prevent connect flakiness in http test

* p2p/simulations: added concurrent goroutines to prevent sleeps on simulation connect/disconnect

* p2p/simulations, swarm/network/simulations: address pr comments

* reinstated dummy service

* fixed http snapshot test

* rawdb: remove unused parameter for WritePreimages func and modify a
spelling mistake

* rawdb: update the doc for function WritePreimages

* metrics, p2p: add ephemeral registry

* metrics: fix linter issue

The lock in StateDB is useless. It's only held in Copy, but Copy is safe
for concurrent use because all it does is read.

ethereum/go-ethereum#16734 introduced BlockHash to the FilterQuery
struct. However, ethclient was not updated to include BlockHash in the actual
RPC request.

core/vm: check empty in extcodehash

Change the type of the metered connection's id field from string to enode.ID.

* swarm, cmd/swarm: address ineffectual assignments

* swarm/network: remove unused vars from testHandshake

* swarm/storage/feed: revert cursor changes

* RequestFromPeers does not use peers marked as lightnode

* fix warning about variable name

* write tests for RequestFromPeers

* lightnodes should be omitted from the addressbook

* resolve pr comments regarding logging, formatting and comments

* resolve pr comments regarding comments and added a missing newline

* add assertions to check peers in live connections

* core: speed up GenerateChain

Use a mock implementation of ChainReader instead of creating
and destroying a BlockChain object for each generated block.

* eth/downloader: speed up tests by generating chain only once

This change reworks the downloader tests so they share a common test
blockchain instead of generating a chain in every test. The tests are
roughly twice as fast now.

* signer: remove ineffectual assignments

* signer: remove ineffectual assignments

* downloader: measure successfull deliveries, not failed

* downloader: fix typos

* swarm: Better syncing and retrieval option definition

* swarm/network/stream: better comments

* swarm/network/stream: addressed PR comments

* swarm: modify context key

* gofmt sctx.go

* swarm: clean up unused private types and functions

Those that were identified by code inspection tool.

* swarm/storage: move/add Proximity GoDoc from deleted private function

The mentioned proximity() private function was deleted in:
1ca8fc1e6fa0ab4ab1aaca06d6fb32e173cd5f2f

* p2p/protocols: introduced protocol accounting

* p2p/protocols: added TestExchange simulation

* p2p/protocols: add accounting simulation

* p2p/protocols: remove unnecessary tests

* p2p/protocols: comments for accounting simulation

* p2p/protocols: addressed PR comments

* p2p/protocols: finalized accounting implementation

* p2p/protocols: removed unused code

* p2p/protocols: addressed @nonsense PR comments