Apostrophe 2.66.0: ckeditor update, apos.utils.escapeHtml works properly in the browser, apos.areas.richText double output fix

[boutell]

• Updated to CKEditor version 4.10.0. The CKEditor build now includes the CKEditor “widgets” feature (not to be confused with Apostrophe widgets). These are essential for modules like the forthcoming apostrophe-rich-text-merge-tags.
• apos.areas.richText and apos.areas.plaintext no longer produce duplicate text. To achieve this, the apos.docs.walk method no longer walks through the _originalWidgets property. This property is only used to preserve the previous versions of widgets that the user lacks permission to edit due to schema field permissions. Exploration of this property by apos.docs.walk led to the observed bug.
• The browser-side implementation of apos.utils.escapeHtml now works properly.