Cleaning up geometry module: New Tipable module

## Enhancement proposal
### New Module
The `geometry` module is extremely crowded (2558 lines, 39 classes).

Therefor I suggest moving the classes connected to arrows to a now module, which could be named `tipable.py`.
This should includes the following:

- TipableVMobject
- Arrow
- Vector
- DoubleArrow
- CurvedArrow
- CurvedDoubleArrow
- ArrowTip
- ArrowCircleFilledTip
- ArrowCircleTip
- ArrowSquareFilledTip
- ArrowSquareTip
- ArrowTriangleFilledTip
- ArrowTriangleTip

### Combining classes
The number of classes is quite a bit over the top in my opinion. I feel like adding an aditional parameter wold be a better choice in many cases:

- Giving Arrow two parameters `double` and `curved` both defaulting to `False` would deprecate DoubleArrow, CurvedArrow and CurvedDoubleArrow (Imo whether CurvedArrow should be deprecated is debatable).
- The ArrowTip should get a parameter `filled` defaulting to `False`. This would deprecate the three filled variant classes.

### Class renamings:
The (remaining) arrow tip classes ought to be renamed:

- ArrowCircleTip => CircleArrowTip
- ArrowSquareTip => SquareArrowTip
- ArrowTriangleTip => TriangleArrowTip, however it might also be a good idea to combine TriangleArrowTip and ArrowTip in ArrowTip.

### Edit: Total Tippable breakdown
After having a chat with @XorUnison I might as well deprecate Tipable and the differnt ArrowTip subclasses all together - we'll see how that turns out :D

## Additional comments
Please add a comment if you want to work on this issue, as it may well be I already started doing so :)