Have Codemirror make PREFIX uris clickable

[CloCkWeRX]

See https://groups.google.com/forum/?fromgroups=#!topic/codemirror/qWu1ZUiBUWM

When presented with a SPARQL query, the prefix URIs should be links.

This allows navigation to the underlying vocabulary, which often has human readable documentation available.

Ideally, the links should have a target="_blank" to open in a new tab