Starting v2.0.0
Add Examples workspace
Add unit tests
Extract logic to new class: ECPercentDrivenInteractiveTransition

- Move layer pausing, continuing, and reversing logic to new class.
- This allows interactive transitions to be more flexible by updating
  frames/transforms directly by providing their own update/cancel/finish
  interactiveTransition calls.
- This is closer to the behavior for the UIKit transition API.
  Interactive transitions can take an existing animation and play it
  back in a "percent driven" manner, or an interactive transition can
  update a view's frame/transform directly.
Interactive transition is now responsible for animation curve
Fix name to be consistent with rest of the API
API for specifying child view layout
Use a navigation controller for home
Change approach for detecting interactive transition

- Transitions are interactive if the delegate method for interactive
  transitions is non-nil.
- The internal interactive transition is triggered by a pan gesture.
WIP. Transition Examples
Tweak default animation

- Linear curve for percent driven animations.
- Ensure the correct frame is set for cancelled transition.
This can crash if the animation already has a transaction
Call these earlier to ensure the state of the context is setup correctly
Hold a strong reference to animationController and interactiveTransition

ECSlidingViewController can loose the reference to these and the
callbacks in completeTransition may crash.
Allow a custom animation to use the default interaction

This is different from how Apple does things with their containers, but
the percent driven interaction for "grabbing" the top view is common and
useful for most animations.
Call user's animation completion block
Let transitions set the frame to whatever they want
Refactor appearance transitions. Also stop using CATransaction.
Implement Fold transition
Do not set topViewController if destination is the same kind of instance

- Useful for just resetting to existing topViewController
- Override this behavior by setting `shouldAlwaysResetTopViewController` to YES in prepareForSegue:sender: