v5.3.1

Changes

• Update System.Reactive package to 4.1.2
• Remove unnecessary dependencies #96 (@soi013)

Other

• Added document comments all public members #88 #89 #90 #91 #92 #93 #94 #95 (@ChrisPulman)

Known issue

• When use on Xamarin.Android project, compile error is occurred. Please check the issue: #87

Thank you for all contributes.