Websocket orderbook buffering (#333)

* Initial commit setting up a map orderbook system with a buffer. It will write to the buffer, sort apply to main orderbook and then process.

* Moves namespaces again

* Updates orderbook to use a sweet new WebsocketOrderbookUpdate type to handle all updates whether its using ID or not. So good. Adds many tests

* Starting to implement orderbook update handling per exchange. Updates namespaces again. Hopefuylly will find a way to update via ID not timestamp, too many endpoints dont provide update timestamps

* Changes orderbookbuffer to use BufferUpdate type instead of orderbook.Base to achieve more functionality and no need for type conversion functions. Updates tests

* Updates all instances of ws.orderbook.Update. Simplifies some orderbook logic

* Introduces toggleable buffer. Renames orderbooks. Completes implementation for everywhere but OKGroup due to hash calculation

* Implements orderbook update for okgroup, but forgets about the orderbook hash checking

* Fixes okgroup checksum calculation. Fixes linting issue. Removes redundant Kraken tests.

* Introduces sorting toggle and separates from buffer toggle. Uses benchmarks to highlight performance gains

* Fixes Gemini rate limit and parsing. Removes comments and fixes typos

* Fixes bitfinex orderbook processing

* Inbuilt sorting, minor fixes for websocket implementations. Improves test coverage

* Adds surprise LakeBTC websocket support

* Fixes data race

* Fixes rebasing issues due to namespace movements

* Addresses PR nits: moves folder namespace from ws to websocket. Removes line spaces in imports. Fixes lakebtc websocket returns and defer fucntions. Fixes comments

* Adds poloniex orderook sorting support

* Enables bitstamp and hitbtc orderbook sorting. Fixes poloniex's sorting

* Renames namespaces and combines monitor and connection into wshandler. Removes unused SPOT const. Changes how orderbook stuff is loaded. It is done in startup with a setup. Removes exchange name from loadsnapshot as well

* Removes the connection.go from rebasing issues. Removes error response from functions used in goroutines

* Fixes test with exchange name output change

* Fixes issues where copy and paste and replace all were used poorly

go.mod

@@ -6,5 +6,6 @@ require (
 	github.com/google/go-querystring v1.0.0
 	github.com/gorilla/mux v1.7.3
 	github.com/gorilla/websocket v1.4.0
+	github.com/toorop/go-pusher v0.0.0-20180521062818-4521e2eb39fb
 	golang.org/x/crypto v0.0.0-20190513172903-22d7a77e9e5f
 )