Flyouts - Off Canvas Custom Content for WordPress 1.4.2

* Updated CMB2 Library to v2.2.6.2
* Removed the CMB2 alpha colorpicker add-on as it is now merged into CMB2 core.
* Minor adjustments to CSS
* Move sidr.js to only enqueue when Flyouts are available within the page.
* Attempt to address iOS behavior with the page still being able to scroll while a Flyout is open.
* Moved codebase to OOP for future re-write.
* Add escaping to translation strings
* Upate translations strings

* Updated: CMB2 Library to v2.2.5.3
* Updated: CMB2 Select2 library to v3.0.3
* Fix: Changed the output crop used for trigger images to full from large.
* Fix: On iOS, the close button was going wonkers due to a webkit/iOS bug with absolute positions.
* Enhancement: compatibility with BNE Theme Framework v1.4.8+
* Enhancement: Move inline JS to the footer using wp_add_inline_script().