Automatically convert Neo fields to Matrix fields when uninstalling the plugin

[benjamminf]

In response to the concern about using Neo given it's a third-party plugin, I figured adding graceful degradation would help people feel more confident using it.

Neo fields and Matrix fields obviously aren't 1:1, so there will be a minor loss of information — specifically, block hierarchy information will be lost — but it's better than losing everything.

[benjamminf]

Converted blocks could have an additional level field created specifically to retain the hierarchy information. Horrible usability, so it'd likely just be removed, but at least it lets you decide what to do with the data. If anyone has any thoughts on this, please let me know!

[benjamminf]

I guess I'll give an update to this feature: it's basically done. The only issue currently is porting content from Neo to Matrix when locales are present. Once this issue is sorted, then it'll be done 👍

[benjamminf]

Now implemented in 1.4.0 which is currently still in testing. If you're interested you can grab the early release from the master branch.