Expose hide() and show() methods

[ghost]

Currently the only way to hide or show the FAB is to call animate() on it. It works, but it is cumbersome because it won't follow swipeAnimation/hideAnimationDuration.

I suggest to move the on("pan") callback code to methods such as hide() and show() because sometimes it is desirable to control this manually.

Thank you

[r0zar]

Agreed, I'm also unable to utilize angular's *ngIf currently.