2.0.0

- WS API v2: added optional auto-reconnect
- WS API v2: added optional packet watchdog
- WS API v2: added optional order packet buffering via multi-op endpoint
- WS API v2: added optional order book & candle managment/persistence
- WS API v2: added optional seq number verification/audit
- WS API v2: added many extra callback/listener funcs (i.e. onMaintenanceStart)
- WS API v2: added ability to mass-unsubscribe listeners by group ID
- WS API v2: most callback methods now support message filtering
- WS API v2: replaced transform logic w/ model classes (i.e. Order)
- WS API v2: many methods now return promises, such as submitOrder()
- REST API v2: transform method updated to match WSv2 class
- REST API v1: minor refactor, methods unchanged
- REST API v2: minor refactor, methods unchanged
- WS API v1: minor refactor, methods unchanged
- BFX constructor exposes & caches clients on `.rest()` and `.ws()` methods
- Updated ws2 examples
- Added model classes (OrderBook, Order, Trade, etc)

1.2.1

- REST API v2: use /candles/ endpoint for candles data
- WS API v2: Candles event provides key
- Improve error message for nonce errors
- Examples: added example for WS2 orders

1.2.0

- REST API v1: Added support for `/orders/hist` endpoint
- REST API v2: Added support for `auth/r/trades/{symbol}/hist` endpoint
- WS API v2: Candles supports now `key` to identify subscription
- REST API v1: Fix `claim_position` argument handling
