Make var userInfo for JSONEncoder and JSONDecoder public (#51)

Fixes #50

Author: fabianfett

Sources/PureSwiftJSON/Decoding/JSONDecoder.swift

@@ -1,6 +1,6 @@
 
 public struct PSJSONDecoder {
-    @usableFromInline var userInfo: [CodingUserInfoKey: Any] = [:]
+    public var userInfo: [CodingUserInfoKey: Any] = [:]
 
     public init() {}
 

Sources/PureSwiftJSON/Encoding/JSONEncoder.swift

@@ -96,7 +96,7 @@ class JSONObject {
 }
 
 public struct PSJSONEncoder {
-    var userInfo: [CodingUserInfoKey: Any] = [:]
+    public var userInfo: [CodingUserInfoKey: Any] = [:]
 
     public init() {}