0.7.0

• Adds mouse support (except pancurses backend for now)
• Adds a ViewWrapper implementation (and therefore an automatic View implementation) for any type that implements DerefMut<Target: View> - this means View is automatically implemented for &mut View, Box<View> ...
• Adds Canvas::wrap(View): this allow to wrap a view and easily override some of its methods.
• Fixes some modifiers detection in ncurses backend