WordPress plugin

• Added the "Try to push all posts" action: pushes all posts in batches with a progress bar.
• Renamed the "Main" page to "Dashboard", split the client and user information into separate cards and added links to the client page, the user profile, the exchange content settings and all news.
• Renamed "Save selected posts" to "Push selected posts" and "Show only selected posts" to "Show only pushed posts".
• Push notices now show the counts of pushed posts and of posts that did not pass validation, with a collapsible list of the validation errors.
• Fixed the "Show only pushed posts" filter listing all posts when no post is pushed.
• Fixed posts of the post types excluded from search being neither listed nor pushed.

• Improved saving and confirming of API credentials action.
• Reworded the invalid API credentials notice to also cover missing credentials.
• Documented the "*" mask for topic tags and blacklist stop words.

• Added a troubleshooting notice to the API and Healthcheck settings tabs.
• Improved the layout and styles of the Main and Statistics pages.
• Improved the responsive view of the Exchange content settings tab.

• Added Help Center links to the Additional information card on the Main page.
• Reworded the admin interface texts to correct grammar and wording mistakes.
• New admin menu icon.

Initial release.