TryUpdate does not call t.trie.TryUpdate(key, value) and calls t.trie.TryDelete
instead. The update operation simply deletes the corresponding entry, though
it could retrieve later by odr. However, it adds further network overhead.

config: add constantinople block to testchainconfig

* core: return error if repair block failed

* make error a bit shorter

- Have `${DataDir}/bzzd.ipc` as IPC path default.
- Respect the `--datadir` flag.
- Keep only the global `--ipcpath` flag and drop the local `--ipcpath` flag
  as flags might overwrite each other. (Note: before global `--ipcpath`
  was ignored even if it was set)

fixes ethersphere#795

trie/database: fix overflow in parent tracking

* params: Add Constantinople block to AllCliqueProtocolChanges

* params: Add Constantinople block to AllEthashProtocolChanges

core: better side-chain importing

* core/blockchain: better printout of receipts in bad block reports

* fix splleing

This should reduce the occurences of travis failures on MacOS

Also fix some linter warnings

Debug traces to investigate a travis issue on MacOS

So that we only see the log message when we actually have to migrate.

downloader: different sync strategy

* trie: return hasher to pool

* trie: minor code formatting fix

* swarm: completed 1st phase of swap accounting

* swarm: swap accounting for swarm with p2p accounting

* swarm/swap: addressed PR comments

* swarm/swap: ignore ErrNotFound on stateStore.Get()

* swarm/swap: GetPeerBalance test; add TODO for chequebook API check

* swarm/network/stream: fix NewRegistry calls with new arguments

* swarm/swap: address @justelad's PR comments