Add possibility to define the behavior of foo:bar URI syntax dynamically

Currently we specifically match "mailto:", "attach:" and "image:" in wikimodel javacc file.

We should recognize all foo:bar syntax as URI and have transformations to dynamically define what to do with each of them based on the keyword before the first ":". If not component is found we could do:

• if the second part starts with double slash it's an URI
• other wise it's a text (to see if we re-parse the text with wiki syntax parser or not)