PublishPress Planner Pro 4.7.2

* Changed: Removed Twig dependency, refactoring the views for using plain PHP templates, #1125;

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* Fixed: Can't send notifications to different Slack channels, or to Slack users. Refactored the Slack integration to use OAuth token in the API instead of the incoming webhook URL. Requires re-authenticating to Slack, #1040;
* Added: Add mew filter before sending Slack messages, "publishpress_slack_message_channel";
* Changed: Deprecated filter "publishpress_slack_actions", replaced by "publishpress_slack_message_actions";
* Changed: Deprecated filter "publishpress_slack_text", replaced by "publishpress_slack_message_text";