Fixes for PHP version 7.2

UX/UI Improvements

• Added ability to close tabs on middle mouse click
• Automatically reset list pagination to the first page when the filter is changed (which would change the results displayed)
• Added align support to non-sortable column headers
• Prevent showing the mail branding menu item to users without the permissions to actually use it
• Display an error if a migration file has been requested by a plugin but doesn't actually exist

API Changes

• Enabled use of unencrypted cookies with the cookie.unencryptedCookies configuration item
• Added showWeekNumber property to the DatePicker FormWidget
• Added support for minifying the core AJAX framework assets when debug mode is disabled
• Added cms.restrictBaseDir configuration item to allow local development to use symlinked files as if they were local to the application root.

Bug Fixes

• Removed circular dependency in the system LESS files
• Fixed issues with using tabs, repeaters, & the JS Trigger API together

Translation Improvements

• Added Slovak (SK) translation