Added filter to modify entire output of JSON+LD function

Added 'wpseo_json_ld_search_output' filter to allow changes to the entire output of the 'internal_search_json_ld' function. This allows user to add code before or after the output, or modify the existing output.

The JSON+LD code currently breaks any site that optimises Javascript with the Autopimize plugin. This new filter allows user to add 'no optimise' tags around the JSON+LD code.
Added a space before the ending )
Bloody hell don't turn off debug. We want to break on notices.
Added an error handler, which produces a stack trace for errors.
Make sure the normal PHP error handler is run too as otherwise PHPunit won't break
Remove error handler as that breaks PHPUnit.
Remove testing of 3.8 as, well, we don't support that anymore now that 4.0 is out the door.
Escaping values given by AJAX-request bulkeditor [#78540238]
Changed esc_html into strip_tags and move it to the method which will be used in all situations.
Codestyle
one more code style thing
Merge pull request #1576 from Yoast/bulk_editor

Escaping values given by AJAX-request bulkeditor [Fixes #78540238]
Merge pull request #1565 from timjrye/patch-1

Added filter to modify entire output of JSON+LD function, props @timjrye
Stripping HTML-tags in preview snippet - Fixes #1561
Strip tags of the title, for page analysis - Fixes #1560
Introduces filter for sitemap base URL, as requested by WPML.
Minor refactor to use DRY-principle.
Grunt all the things.
Add new build task
The first output of all those Grunt tasks
Merge branch 'master' into preview_snippet
Merge commit '417a01cda239cbb22a24728cc86c8d63c41165e4' into preview_snippet