Memory + behaviour leak when destroying CKEditor instances

[Colonel_mortis]

When an ips.ui.editor instance is destroyed, you are following the answer from a Stack Overflow question and trying to manually destroy the CKE instance. Unfortunately, that manual destruction is not sufficient, and is leaving references to the editor and behaviour. Take ipsautosave as an example (and maybe the only example, I've not looked further) - it maintains a reference to `editor`, and runs autosave on it every two seconds. It attaches a `destroy` event handler, which would be triggered when calling editor.destroy(), to cancel the timeout and therefore release the editor reference, but because you never trigger the destroy event it's not sufficient. (I'm noticing this because I am trying to use multiple editors on a page with the same autosave key, but it's still a problem without that.) It looks like there are a few other references that destroy manually cleans up, so there are presumably a few other things that are leaked too.

At a minimum, you should be doing `editor.fire("destroy")` to trigger all of that cleanup code, but ideally you should find the things that prevent editor.destroy() from working and fix those in CKE. As a middle ground, maybe you could do `try { editor.destroy(); } catch (e) { /* existing manual best effort */ }`.

[bfarber]

Thanks, I've logged an issue internally to have this checked on for our next release. Appreciate the feedback!