Perfmatters 2.4.3

* Added new option to lazy load CSS Background Images.
* Added new option for Dual Tracking when using gtag.js in local analytics.
* Added new perfmatters_rest_api_exceptions filter.
* Fixed an issue where individually delayed local scripts would not get correctly rewritten to load from the CDN.
* Fixed an issue where lazy loading would run into an error if no px or % was specified with the threshold value.
* Fixed an issue with buffer validation that was conflicting with certain caching setups.
* Fixed an issue where existing font preconnect and prefetch tags were not being being detected properly when using Local Fonts.
* Fixed an error related to cookie constants when running MU Mode in certain environments.
* Fixed multiple AMP validation errors and added additional checks to prevent certain functions from running on AMP URLs.
* Minor adjustment to CDN rewrite regex pattern to work with encoded quotation characters.
* Changed toggle CSS selectors to be more specific to prevent conflicts.
* Moved plugin settings header output to in_admin_header action hook for compatibility.
* Moved JS optimization functions to new class structure to be more inline with current codebase.
* Improvements to critical image preloading allowed for a move to a singular output buffer.

* Fixed an issue that was causing excluded selectors to not be recongnized properly after Used CSS was cleared.
* Minor adjustments to the new plugin UI.

* Updated plugin settings UI.
* Added new post meta option to Clear Used CSS for an individual page or post type.
* Added new perfmatters_rucss_excluded_selectors filter.
* Fixed a lazy loading issue that was preventing some images from loading properly in Safari.
* Migrated Delay JS Timeout dropdown to a simpler on/off toggle that will default to 10 seconds. Our filter is also still available to set a custom timeout value.
* Fixed an issue with MU plugin that was interfering with rewrite rules in some instances.
* Added additional excluded page builder parameter for Flatsome UX.
* Moved restore default functionality to a separate option on the tools page.
* Code refactoring.
* Translation updates.