Merge Teleport and TeleportFull?

`TeleportFull` seems like a misuse of leveraging default key-word args.

---

For reference, `Teleport` is defined as
```python
controller.step(
action='Teleport',
x=0.999, y=1.01, z=-0.3541)
```
and `TeleportFull` is defined the same way, but with 2 extra args:
```python
event = controller.step(
action='TeleportFull',
x=0.999, y=1.01, z=-0.3541,
rotation=dict(x=0.0, y=90.0, z=0.0),
horizon=30.0)
```

---

What would seem easier from a user's perspective would be to allow users to **optionally** specify the `rotation`, `horizon`, and also `x`, `y`, `z` positions. And for all the options that are not specified, leave them **as is**.

For example, running
```python
controller.step(
action='Teleport',
x=0.999, z=-0.3541,
horizon=-30)
```
Will change only the x/z position and horizon of the agent, and leave the y/rotation as is. This will make it so that users don't have to know some crazy float `y` value that's only accessible from `GetReachablePositions`.

Effectively, this should depreciate the need for `TeleportFull` since all it's functionality would be merged with `Teleport`.