* Add mouse grab
We now also send mouse movement events only to the interested view.
* Add deprecation messages handler
* Make various `View`s respect `on_mouse_left`
* `StatusView`
* `TitleView`
* `TreeView`
* `ToolbarView`
* Fix scrollbar in `TreeView` not updating
We were in some cases sending outdated mouse positions to the scrollbar,
which made it think that the mouse was hovering it.
This also updates the hovered item more responsively during scroll.
Now toolbarview always compute up-to-date sizes and spacing to adapt to
changes in icon big font.
For treeview and toolbarview revert the goto_size approach to use the
original approach of rxi/lite. In order to make it work when user resizes
dragging the divider we use the view optional method set_target_size().
This latter changes the view's target size instead of changing its size
right away. The size is only changed by the lite's layout and animation
system.
Remove the config.treeview_size variable that was no longer working because
plugins are loaded before the user's config.