* Handle some web3 timeouts better
* Add support for developer .env files
* Eth1 improvements; Mainnet genesis state
Notable changes:
* The deposits table have been removed from the database. The client
will no longer process all deposits on start-up.
* The network metadata now includes a "state snapshot" of the deposit
contract. This allows the client to skip syncing deposits made prior
to the snapshot (i.e. genesis). Suitable metadata added for Pyrmont
and Mainnet.
* The Eth1 monitor won't be started unless there are validators attached
to the node.
* The genesis detection code is now optional and disabled by default
* Bugfix: The client should not produce blocks that will fail validation
when it hasn't downloaded the latest deposits yet
* Bugfix: Work around the database corruption affecting Pyrmont nodes
* Remove metadata for Toledo and Medalla
This also assigns precise types to the constants in the minimal
and mainnet presets in order to reduce the chance of compilation
errors when custom presets are used (previously, only the custom
presets have precisely assigned types for the constants).
* reorder ssz
* split into hash_trees and ssz_serialization, roughly, for hashing and
IO
* move bitseqs into ssz (from stew)
* clean up imports
* docs, imports