Add `redis-call` fn for raw Redis requests (suggestion by 'ToBeReplaced')
Modify `make-conn-pool` for common-use case: nil pool-opts now gives default pool

This previously gave a degenerate pool which is a pretty uncommon desire. The
`{}` conn idiom now gives more sensible behavior by default.

A degenerate pool can still be created by using `:none` for the pool opts.
Update TODOs
Protocol housekeeping: spare the poor !s
Merge branch 'tundra' into v2.0.0
BREAKING: Unserialized bytes no longer wrapped in vec

This was a silly decision since array .length is O(1) anyway and
probably cheaper than the vector destructuring. Dropping the unnecessary
wrapping is more consistent and allows easier tooling (e.g. parsers).
Update README
~WIP Tundra