[TASK] Several bugfixes and feature additions

Bugfixes
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* Pagination is not working
* CategoryMenu content element not working
* Page reload is missing at some places when something is changed in the inspector

Features / Improvements
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* Validations (inspector) - added validations wherever possible for the properties edited in inspector
* Archive menu - new node type is now available which renders the year and montwise archive menu
* News tags - Comma separated tags can be added to news item and then filtering of news list by a tag is possible
* RSS feed - Add .rss extension to any News Folder node and you can see the RSS feed of that folder
* Meta tags - Keyword and description meta tags are rendered on news single pages