proposal: Add support for platform animation

Is your feature request related to a problem? Please describe.

Currently all we have is the ability to tell Sextant to animate or not.

Describe the solution you'd like

I have seen a few custom animation libraries for Xamarin.Forms. What I would like is from Sextant is the ability to abstract platform level animations and allow better support for animations. Change the API from taking a bool to maybe an enumeration where the consumer can dictate which platform animation to use. What would be great is the ability to provide your own animations that have platform specific implementations.

Describe suggestions on how to achieve the feature

The following are extensions that should get us where we want to be in some fashion.

Documentation

• Xamarin View Extensions
• Xamarin Animation Extensions
• iOS Graphics Animations
• iOS Core Animations
• Android View Animations
• Android Drawable Animation

GitHub Projects

• Xamarin Forms Page Transitions

Start by reviewing Sextant's current navigation API and its boolean animation option, then compare the Xamarin.Forms ViewExtensions and AnimationExtensions references with the linked iOS and Android animation guidance. Done would mean a defined abstraction for platform animations, including selectable platform behavior and a way for consumers to provide platform-specific custom animations.