Option to choose frames or seconds display in AnimationPlayer's timeline

[joelgomes1994]

The timeline in AnimationPlayer, by default, shows the time in seconds, and the cursor snaps to the seconds subdivisions instead of individual frames.

This is not good when importing an external animation made through frames reference (like importing from Blender), and when is needed to have more precision too. I suggest to add an option to toggle the individual frames display (changing the grid and snapping as well).

And a question: Godot have an animation frame rate parameter? Thanks.

[akien-mga]

Fixed by 4203266.