Tofe/architecture work

The following has been implemented here:
 - creation of a WindowManager component, inherited by the root component, to cleanly separate the things related to the window management from the rest (like the design of the LSM main view)
 - round corners for all the windows, plus a drop shadow. This has been done in the WindowContainer component.
 - basic Gestures: up and down mean return to card view
 - rework of window state management, more centralized in the WindowManager