- `trio_typing` is nearly obsolete since `trio >= 0.23`
- `exceptiongroup` is built-in to python 3.11
- `async_generator` primitives have lived in `contextlib` for quite
a while!
First attempt at getting `multiprocessing.shared_memory.ShareableList`
working; we wrap the stdlib type with a readonly attr and a `.key` for
cross-actor lookup. Also, rename all `numpy` specific routines to have
a `ndarray` suffix in the func names.
More or less a verbatim copy-paste minus some edgy variable naming and
internal `piker` module imports. There is a bunch of OHLC related
defaults that need to be dropped and we need to adjust to an optional
dependence on `numpy` by supporting shared lists as per the mp docs.