Nitdoc next

Some improvments for Nitdoc:

* **Better display of big class hierarchies in lists and graphs**: example with class Token: http://gresil.org/jenkins/job/CI-nitdoc/ws/doc/nitc/class_workspace__Token.html

* **Markdownize synopsys**: example with Concerns here: http://gresil.org/jenkins/job/CI-nitdoc/ws/doc/nitc/group_workspace__workspace.html#concerns

* **Better display for mpropdefs definition hierarchies**: example with the `Object::exit` method: http://gresil.org/jenkins/job/CI-nitdoc/ws/doc/nitc/class_standard__Object.html#standard__Object__exit

Also some minor fixes:

* add link to source even in local generation (link to the file so it can be openned in a browser but there is no jumps to lines)
* always redirect to mproperty definition in class page (try to hidde at a maximum the mproperty page so it only accessible from intro definition)

Previews:

* lib: http://gresil.org/jenkins/job/CI-nitdoc/ws/doc/stdlib/index.html
* nitc: http://gresil.org/jenkins/job/CI-nitdoc/ws/doc/nitc/index.html