Provide a way to reset the player

[HenryLoenwind]

Please provide a way to reset the player, i.e. to set a provided position and look vector, cancel all abilities, and cancel all momentum.

Use cases:

• Teleporting the player around the map
• Changing the environment around the player
• Returning from a pause/menu screen

While this can be accomplished by unloading and loading the player scene, doing so is overkill and may have further-reaching impacts. For example, I have all kinds of menu screens and overlays tied to the player scene node (that's where the camera is, after all...) that are connected with all kinds of exports and signals to the game logic: