Consider `impl Into<PointX<_>>` in kiss3d API

A series of `From` traits are defined on `Point` type ([doc](https://docs.rs/nalgebra/0.21.1/nalgebra/geometry/struct.Point.html#impl-From%3C%5BN%3B%201%5D%3E)). We could combine it with `impl Into>` to help user to write more compact syntax.

For example, the [Window::draw_line](https://docs.rs/kiss3d/0.24.1/kiss3d/window/struct.Window.html#method.draw_line) receives a pair of point and color. We can turn it to the following.

```rust
pub fn draw_line(
&mut self,
a: impl Into>,
b: impl Into>,
color: impl Into>
)
```

In this way, we can call by `window.draw_line([0.0, 0.0, 0.0], [0.8, 0.8, 0.8], [1.0, 1.0, 1.0])` instead of `Point3::new()` everywhere.

Start with Window::draw_line and compare its current signature with nalgebra's Point From implementations linked in the issue. Check the surrounding window API and existing tests or examples; done means the intended point and color inputs compile in the compact array form without breaking existing calls.

Written by the indexing model from the issue text.