Implement a (fulltext) search over in all XML documents

[simar0at]

BaseX should be able to efficiently search all documents and it has fulltext search capabilities albeit not as sophisiticated as NoSkE.
This is a low priority enhancement.

• First we should try a quick implementation using BaseX fulltext search
• As a further enhancement we can think about creating NoSkE verticals of all the XML and use it

The second option seems a bit too much as NoSkE's capabilities most useful really with corpus texts and our experience is that there are not so many users that try the advanced searches.