[Feature request] Conditional enabling of items or slots

[TheEmi]

In the small project i've built i wanted 2 things from swapy:

1. Not change styling during the animation (already set to "none")
2. Disable specific items or slots.

This would be of great help, not only to me but to push swapy to a more controlled environment.
Being able to drop out of default behaviour and define your own is often what devs look for.

Thank you!