Added controller. hint() to trigger UI hint

[ciriousjoker]

Fixes #32

• Version bumped to 0.5.0

Usage

FlipCardController _controller = FlipCardController();
 
 _controller.hint(
   // optional
   duration: Duration(milliseconds: 400),
   // optional
   total: Duration(milliseconds: 900),
 );
 
 FlipCard(
   direction: FlipDirection.HORIZONTAL,
   controller: _controller,
   onFlip: () {
     //
   },
   back: Center(
     child: Container(
       child: ProjectFrontWidget(
         project: widget.project,
       ),
     ),
   ),
   front: Container(
     color: Colors.red,
     child: Center(
       child: ProjectBackWidget(
         project: widget.project,
       ),
     ),
   ),
 );

The duration will only run if not flipped yet and not already animating.
Animation runs for duration and reverses afterwards. The total duration will be used for this animation only and resets afterwards.

[ciriousjoker]

Actually, don't merge this just yet, I'll clean up the syntax and expose the controller as well to allow more control from outside.

[ciriousjoker]

Even if GlobalKeys are possible, Controllers are preferred. The controller that's introduced by this PR also provides the ability to access widget state if required.

This can be merged if you want, it's stable now.

[ciriousjoker]

@fedeoo Could you please merge this?

[ciriousjoker]

0.5.1 solves a use case where the card is aligned to the top (which can't be changed from outside this package)

[fedeoo]

Merged in this PR. #39
I'm closing this one. Thanks for your work.
I hope @BrunoJurkovic or you can help to maintain this repo as I am not working with flutter now.