Respect prefers-reduced-motion setting

[sophiekoonin]

Fixes #26

Extremely copy-pastey, but it seems like each cursor is its own encapsulated thing so it seemed like the thing to do.

• check prefers-reduced-motion when we init the cursor trail
• when the value of prefers-reduced-motion changes, either re-init or destroy the cursor trail
• add an id to the trail's canvas element, so that we can remove it from the DOM where necessary (this may help with #33?)

[tholman]

Awesome! A few small bits that we'll need to patch up here

• We should be able to remove the canvas from its saved element this.canvas rather than having to give it an ID/request to select it again.
• Will also need to run a cancelAnimationFrame to stop the primary loop from running in the background
• We should also remove all the event listeners when the destroy happens
• I was also thinking maybe when init is ran with prefers reduced motion we should drop a small console log to let people know, for good measure

Sorry its a pita to update each of these, if we get one of these in the green I'll happily go through and patch the others

[tholman]

I'm going to merge and then add these lil bits now!

[tholman]

Completed the rest here! https://github.com/tholman/cursor-effects/commit/c4b4aef2cd371d2c32b23d903ccb65c0be5a4a64 ... looking and behaving well by all my tests :)