Update to 4.0.0-alpha.3 - Response Engines, 'inject' the context.JSON/JSONP/Text/Data/Markdown/Render, Read HISTORY.md

## 4.0.0-alpha.2 -> 4.0.0-alpha.3

**New**

A **Response Engine** gives you the freedom to create/change the
render/response writer for

- `context.JSON`
- `context.JSONP`
- `context.XML`
- `context.Text`
- `context.Markdown`
- `context.Data`
- `context.Render("my_custom_type",mystructOrData{},
iris.RenderOptions{"gzip":false,"charset":"UTF-8"})`
- `context.MarkdownString`
- `iris.ResponseString(...)`

**Fix**
- https://github.com/kataras/iris/issues/294

**Small changes**

- `iris.Config.Charset`, before alpha.3 was `iris.Config.Rest.Charset` &
`iris.Config.Render.Template.Charset`, but you can override it at
runtime by passinth a map `iris.RenderOptions` on the `context.Render`
call .
- `iris.Config.IsDevelopment` , before alpha.1 was
`iris.Config.Render.Template.IsDevelopment`

**Websockets changes**

No need to import the `github.com/kataras/iris/websocket` to use the
`Connection` iteral, the websocket moved inside `kataras/iris` , now all
exported variables' names have the prefix of `Websocket`, so the old
`websocket.Connection` is now `iris.WebsocketConnection`.

Generally, no other changes on the 'frontend API', for response engines
examples and how you can register your own to add more features on
existing response engines or replace them, look
[here](https://github.com/iris-contrib/response).

**BAD SIDE**: E-Book is still pointing on the v3 release, but will be
updated soon.

config/iris.go

@@ -2,13 +2,13 @@ package config
 
 import (
 	"github.com/imdario/mergo"
-	"github.com/iris-contrib/rest"
 )
 
 // Default values for base Iris conf
 const (
 	DefaultDisablePathCorrection = false
 	DefaultDisablePathEscape     = false
+	DefaultCharset               = "UTF-8"
 )
 
 type (
@@ -89,12 +89,14 @@ type (
 		// default is false
 		IsDevelopment bool
 
+		// Charset character encoding for various rendering
+		// used for templates and the rest of the responses
+		// defaults to "UTF-8"
+		Charset string
+
 		// Sessions contains the configs for sessions
 		Sessions Sessions
 
-		// Rest contains the configs for rest render configuration
-		Rest rest.Config
-
 		// Websocket contains the configs for Websocket's server integration
 		Websocket *Websocket
 
@@ -111,9 +113,9 @@ func Default() Iris {
 		DisableBanner:          false,
 		DisableTemplateEngines: false,
 		IsDevelopment:          false,
+		Charset:                DefaultCharset,
 		ProfilePath:            "",
 		Sessions:               DefaultSessions(),
-		Rest:                   rest.DefaultConfig(),
 		Websocket:              DefaultWebsocket(),
 		Tester:                 DefaultTester(),
 	}