Since it's depended on by `.data` stuff as well as pretty much
everything else, makes more sense to expose it as a top level module
(and maybe eventually as a subpkg as we add to it).
In cases where a brokerd backend doesn't yet support a symcache we need
to do manual `.get_mkt_info()` queries and stash them in a table that we
pass in for the mkt failover lookup to `Account.update_from_ledger()`.
Set the `PaperBoi._mkts` to this table for use on real-time ledger
writes in `.fake_fill()`.
Since crypto backends now also may expand an FQME like `xbteur.kraken`
-> `xbteur.spot.kraken` (by filling in the venue token), we need to use
this identifier when looking up per-market order dialogs or submitting
new requests. The simple fix is to simply look up that expanded from
from the `Feed.flumes` table which is always keyed by the `MktPair.fqme:
str` - the expanded form.
It's finally a decent little design / interface and definitely can be
used in other backends like `kraken` which rolled something lower level
but more or less the same without a wrapper class.
Tyler Goodlet