Update to Bevy 0.13

[ThierryBerger]

Builds on top of https://github.com/dimforge/sparkl/pull/23 to update to bevy 0.13.

The update went quite smoothly ; I didn´t make a full audit of the code to use newest API.

:warning: This PR still has the hardcoded access to instance_index from bevy 0.12 update. The code is currently slightly changed in an attempt to make it less hardcoded, but I'm not convinced and would appreciate guidance.