* Test: Internal exchange coverage
* Tests: Rename exchange.TestInstance to Setup
This package function is either going to be imported and used as just exchange.Setup,
or more likely testexch.Setup.
This removes the Stutter of having
internal/testing/exchange.TestInstance which is implicit given the
package path
* Kraken: Fix wsCancelOrders not erroring order id
We were using the "cancel many" facility of the Kraken api.
However since that doesn't actually report errors individually, it seems
saner to just multiplex over it.
We were going to get N+ responses anyway. Might as well send N+ requests
* Common: Add ErrorCollector and methods
* Binance: Fix subscription failures ignored
* Testing: Fix race on shared config singleton
* Config: Privatise Global config var
We should *either* use a private var *or* use an accessor, but it
doesn't make sense to mix paradigms.
Since GetConfig() is well established this instead removes the limited uses of direct public access and adds a Setter
* Zip: Fix test failure on http mocks
* Websockets: Move Subscription to its own package
This allows the small type to be imported from both `config` and from
`stream` without an import cycle, so we don't have to repeat ourselves
* Subs: Renamed Currency to Pair
This was being mis-used through much of the code, and since we're
already touching everything, we might as well fix it
* Websockets: Add Subscription configuration
* Binance: Add subscription configuration
* Kucoin: Subscription configuration
* Simplify GenerateDefaultSubs
* Improve TestGenSubs coverage
* Test Candle Sub generation
* Support Candle intervals
* Full responsibility for formatting Channel name on GenerateDefaultSubs
OR consumer of Subscribe
* Simplify generatePayloads as a result
* Fix test coverage of asset types in processMarketSnapshot
* Exchanges: Abstract ParallelChanOp
* Tests: Generic ws mock instances
* Kucoin: Fix intermittent conflict in test currs
Use isolated test instance for `TestGetOpenInterest`.
`TestGetOpenInterest` would occassionally change pairs before
GenerateDefault Subs.
