Fixes for issues #133 and #141

[marekrozmus]

Closes #133,
Closes #141

[jcuenod]

I didn't look in a great level of detail but does this support the delete animation when swiping both left and right? It looked like it was just the one way but, like I say, I didn't look in detail at what was going on, let alone actually test the PR.

Thanks for this! The sample gif you posted looks awesome and is exactly what I had in mind.

[marekrozmus]

There will be both left and right animations in finished implementation. Thanks for pointing that out :) I'll remember about this from now on :)

[przemyslawzalewski]

Overall, looks great! Thanks for picking a transition-group based solution for this issue so no responsibilities are duplicated.
Anyway, could the basic example be kept and both of these displayed so for basic usage the example is a little simpler but right below, usage of transitions is showcased in a separate section/page?

[przemyslawzalewski]

Consider typing SwipeableList children to allow properly typed callback as a child.

[jcuenod]

This looks excellent

[przemyslawzalewski]

Good job!