Add missing library for itkDataImagePlugin

Added a test for nested var names
introduce medDataSourceManager, remove patient navigator from the workspace area
Move all the non gui code from browserArea to the dataSourceManager.
add the compact data base view to the workspace area.
get rid of the navigator
restablish API of medAbstractDataSource
Fix Crash at lunch time
DataSource are created in the constructor of the manager, add accessor to dataSources, remove useless signal / slots
Disable double click on Study and Parent entry of the database.
remove database preview
add a basic QGraphicsVirw to embed thumbnails in database compactview
find a way to have a nice resize of the preview
add medDatabaseThumbnailHelper to fix size ot the tumbnails
fix 4d thumbnail generation
fix initialisation of preview (set minimal size)
recompute stylesheet of the navigator