Factor out an API object

Relates to #333

apiobject.go

@@ -0,0 +1,19 @@
+package webrtc
+
+// API is a repository for semi-global settings to WebRTC objects
+// In the simplest case, the DefaultAPI object should be used
+// rather then constructing a new API object.
+type API struct {
+	settingEngine settingEngine
+	mediaEngine   MediaEngine
+}
+
+var defaultAPI = NewAPI()
+
+// NewAPI Creates a new API object for keeping semi-global settings to WebRTC objects
+func NewAPI() *API {
+	a := new(API)
+	initSettingEngine(&a.settingEngine)
+	InitMediaEngine(&a.mediaEngine)
+	return a
+}