Surface Swimming addition: Treading Water and Diving

Prologue:

One of the best parts of 1.13 has definitely got to be the swimming changes that added more maneuverability to underwater movement. However, it sadly did little for swimming on the surface. Here's how that might be fixed.

Treading Water:

When the player surfaces, they should automatically tread water (at least when above a certain amount of hunger, meaning you would eventually drown after you became hungry, if you didn't put effort in).

Think of what Link does in most Legend of Zelda games when swimming on the surface of the water. You can just leave him and he'll idle there without drowning.

When the player is treading water, their head will be kept above the surface without having to constantly press/hold the space bar to keep from sinking an losing breath.

From here, the player will not sink or rise without input, but can look around freely and move in any horizontal direction (preferably with animation) while doing so by using the direction keys. The player can also go into the new quick swimming mode without needing to be submerged (having their head under water).

note: The player must surface to begin treading water. If they jump into water from a high place, they will still plunge deep into it as opposed to suddenly throwing all velocity out of the game window and stopping at the surface of the water.

Diving:

When treading water, if the player wants to go below the surface, they must actively do so by either crouching, or looking downward while swimming quickly (the sprint-swimming).