Replace the patient Navigator with a compact database view.

Sorry for the mess, it will need to be rebase when/if  the PR #102 is merged. Just let me know if it suits you that way.  The thing is that without the changes in the qss, the widget for the database in the workspace area is realy badly integrate.

Remember that we intend to add a thumbnail at the bottom of the left pannel in the workspace area as well as in the browser area (instead of the dadabasePreview widget) . Comming soon in another PR.

The dataSources are now managed by a singleton, medDataSourceManager. For less non GUI code in the browser area.