* Implement subscriptions and filtering
* Add e2e test with log filter polling logs from EVM with clique backend
* Apply review comments
* Move devnode to t/devtests to avoid cycle in imports
Some operations (like deploying contracts) require filter APIs to work.
Since these operations aren't supported on Infura anymore, and we don't
run LES, a separate implemenation of filters is required.
Signed-off-by: Igor Mandrigin <i@mandrigin.ru>