RFC: Adding a presave hook in editor focusoutHandler

[andrewshell]

I'm curious if there have been any conversations about providing hooks in the code to allow plugins to extend core functionality. Here is an example of adding a "presave" hook to the editor.

I've created a plugin that would use this hook as a proof of concept.

https://github.com/andrewshell/wiki-plugin-metadata/blob/master/client/metadata.js#L26-L35

I'm sure there will need to be discussions before something like this gets merged. So I'm documenting the idea with working code.

[dobbs]

A while back I created a feature to allow plugins to override the editor. It's not the same thing as the presave hook you've proposed, but I think reaching for similar kinds of extensions.
#247