New functionalities :
* Added project properties window with webcam detection
* Added Preferences dialog
* Added Management of themes : Tropical themes by default
* Added hide/show of trash in capture treeview
* Image thumb : size increase
* Disallow move of image inside capture treeview
* On Montage a selection of image launch image preview, instead of double click
Fix for :
* luciole crash during project load
* luciole crash during image import
* mixer error when acquisition started
* missing OK/cancel button on assistant filechooser
* missing save as button
* missing quit action button