Fix #595 TileLayer not getting disposed correctly

[kuhnroyal]

Correctly dispose TileLayer and Tiles in the order required by the TickerProviderStateMixin. The AnimationController in the tiles was not being disposed at all. After this change _pruneTiles sometimes gets called after the widget is already disposed - added a mounted check to prevent this.

[maRci002]

This is the proper way to dispose AnimationController.

[kuhnroyal]

Would be nice to get this into a new release. 0.9.0 is unusable for me.

[maRci002]

You can still use your fix as dependency until new release:

  flutter_map:
    git:
      url: git://github.com/johnpryan/flutter_map.git
      ref: a00355b13951605e88e6a16152f18852886a387e

Or:

  flutter_map:
    git:
      url: git://github.com/kuhnroyal/flutter_map
      ref: fix-tilelayer-dipose

[kuhnroyal]

I know ;)