* Update project to use Whisper v6. Part of #638
* Revert "Add patch to downgrade usage of Whisper v6 to v5 in some geth 1.8.1 vendor files. Part of #665" - this reverts commit 6aefb4c8fd02dbcfffac6b69e8bb22b13ef86b6b.
* Enable light mode on Whisper v6 for non-mail servers. Part of #638
* Fix race condition in whisperv6/peer.go. Part of #665 (PR already accepted upstream for 1.8.2)
* Update bootnode addresses in staticnodes.json. Part of #638
* Add `shh.lightclient` flag and tests for bloom filter setting logic. Part of #638
* Move MakeTestNodeConfig to utils. Part of #638
* Reduce PoW in `whisper_jail_test.go` to fix flaky test. Part of #638
Test waits till synchronization is started, then interrupts network connection, wait for a failure event and restore network connection, confirming that after the connection is restored synchronization will proceed.
Network disconnect is introduced by removing default gateway, easily reversible condition.
On my local machine it takes 30 seconds for peers to reconnect after connectivity is restored. As you guess this is not an accident, and there is 30 seconds timeout for dial expiration. This dial expiration is used in p2p.Server to guarantee that peers are not dialed too often.
Additionally I added small script to Makefile to run such tests in docker environment, usage example:
```
make docker-test ARGS="./t/destructive/ -v -network=4"
```
Pedro Pombeiro
Dmitry Shulyak