v0.9.0

This release has some API changes. Here is a list of all changes in release:

Incompatible changes:
- (*Client).Close: changed from func(*Disconnect) error to func(*Disconnect) chan error
- (*Client).Handle: removed
- Config.ClientPresencePingInterval: removed
- NewClient: changed from func(context.Context, *Node, Transport) (*Client, error) to func(context.Context, *Node, Transport) (*TransportClient, CloseFunc, error)
- NodeEventHub.ClientRefresh: removed
- RefreshHandler: changed from func(context.Context, *Client, RefreshEvent) RefreshReply to func(RefreshEvent) RefreshReply
Compatible changes:
- (*ClientEventHub).Presence: added
- (*ClientEventHub).Refresh: added
- CloseFunc: added
- Config.ClientPresenceUpdateInterval: added
- ConnectReply.ClientSideRefresh: added
- PresenceEvent: added
- PresenceHandler: added
- PresenceReply: added
- RefreshEvent.Token: added
- RefreshReply.Disconnect: added
- TransportClient: added

Now let's try to highlight most notable changes and reasoning behind:

• NewClient returns TransportClient and CloseFunc to limit possible API on transport implementation level
• ClientPresencePingInterval config option renamed to ClientPresenceUpdateInterval
• Centrifuge now has client.On().Presence handler which will be called periodically while connection alive every ClientPresenceUpdateInterval
• Client.Close method now creates a goroutine internally - this was required to prevent deadlock when closing client from Presence and SubRefresh callback handlers.
• Refresh handler moved to Client scope instead of being Node event handler
• ConnectReply now has new ClientSideRefresh field which allows setting what kind of refresh mechanism should be used for a client: server-side refresh or client-side refresh.
• It's now possible to do client-side refresh with custom token implementation (example)
• Library now uses one concurrent timer per each connection instead of 3 - should perform a bit better

All examples updated to reflect all changes here.