This commit introduces the Validator interface, which
is intended to be implemented by any sub configs. It
specifies a Validate() error method that should fail
if a sub configuration contains any invalid or insane
parameters.
In addition, a package-level Validate method can be
used to check a variadic number of sub configs
implementing the Validator interface. This allows the
primary config struct to be extended via targeted
and/or specialized sub configs, and validate all of
them in sequence without bloating the main package
with the actual validation logic.
Bumps the default read and write handlers to be well
above the average number of peers a node has. Since
the worker counts specify only a maximum number of
concurrent read/write workers, it is expected that
the actual usage would converge to the requirements
of the node anyway. However, in preparation for a
major release, this is a conservative measure to
ensure that the default values aren't too low and
improve network instability.
