EventMgr, SetRectMgr, DrawMgr; misc

[dhardy]

• Clippy now runs on stable and nightly, without forcing warnings into errors on nightly
• Renamed: Manager -> EventMgr, ManagerState -> EventState
• Added: fn WidgetCore::identify(&self) returning a printable object (e.g. Canvas#0)
• Added: fn WidgetChildren::is_strict_ancestor_of(&self, id: &WidgetId)
• Layout::size_rules now takes size_mgr: SizeMgr parameter (new type wrapping SizeHandle)
• Layout::set_rect now takes mgr: &mut SetRectMgr parameter (new type, able to construct SizeMgr and accept TkAction, constructible from EventMgr)
• Layout::draw now takes parameter draw: DrawMgr (new type, able to construct SizeMgr, SetRectMgr and EventState
• Move kas_core::draw::handle and kas_core::draw::theme private modules to new kas_core::theme module
• Replace WidgetCore::input_state with EventMgr::draw_state
• Fix closing non-parent popups when opening a new popup
• Combine touch and mouse movement events within a single frame
• Rename Quad::with_coords and with_pos_and_size to Quad::from_coords and from_pos_and_size
• Add updatable data versioning
• DragHandle is now never keyboard-navigable (simpler logic)
• Some more methods have #[must_use]
• Fix pop-up menu open/close on mouse hover