Implementation of syntax highlighting

The first commit introduces a new package (poc.highlight) that handles syntax highlighting for templates.

* Document partitioner: 
A change was necessary in order to have all the document parsed again on source update.

* Source viewer configuration: 
The new scanner had to be provided to the DefaultDamagerRepairer

* Highlight: 
canners, rules and tokens have been added


The second commit introduces a fix to the error that was raised as soon as a newly created file was edited.

* Document partitioner: 
The typed region was not correctly initialized