Update TinyMCE to the current development version 4.0.21+

[azaozz]

There is a change in the current development version of TinyMCE that is needed in order to fix the adding of invalid/incorrect undo levels caused by updates inside wpviews: ​https://github.com/tinymce/tinymce/commit/60decfb411c75460793997bc21848682f963aacd

[azaozz]

The only other change is a fix for requireLangPack() in old plugins which is nice to have too: ​https://github.com/tinymce/tinymce/commit/dc4a1e6ee584d12cad5ebe06eb699bcc25ad1c24

Changelog since 4.0.21:

Added lastLevel to BeforeAddUndo event so it's easier to block undo level creation based on lastLevel data.
Fixed so old language packs get properly loaded when the new longer language code format is used.

[azaozz]

In 28066:

Update TinyMCE to the current development version, 4.0.21.1. Fixes #27744

[azaozz]

In 28138:

Update the TinyMCE tests to 4.0.21.1, see #27744

[programmin]

Any chance of updating this to 4.0.26 in the near future? Or would that be for next major release 4.0?

It fixes dozens of bugs in the current Tinymce 4.0.21 - see #28250

Thanks

[azaozz]

Replying to programmin:

Ha, coincidence? Been testing the update to 4.0.26 this afternoon :)