wayland: implement scaling

This involves many subsystems:

- config:
    - allow setting the connector scale
    - allow setting the cursor size
- cursors:
    - load server cursors for all requested sizes and scales
- wl_surface:
    - track the output the surface belongs to
    - send wl_surface.enter/leave
- wl_output:
    - implement wl_output.scale
- text:
    - pre-render texts for all used scales
- renderer:
    - properly align scale textures and rectangles
- wp_fractional_scale:
    - new interface for fractional scaling

src/ifs/wl_surface/xwindow.rs

@@ -12,7 +12,7 @@ use {
         state::State,
         tree::{
             Direction, FindTreeResult, FoundNode, Node, NodeId, NodeVisitor, StackedNode,
-            ToplevelData, ToplevelNode,
+            ToplevelData, ToplevelNode, WorkspaceNode,
         },
         utils::{clonecell::CloneCell, copyhashmap::CopyHashMap, linkedlist::LinkedNode},
         wire::WlSurfaceId,
@@ -401,6 +401,10 @@ impl ToplevelNode for Xwindow {
         Some(self.surface.clone())
     }
 
+    fn tl_set_workspace_ext(self: Rc<Self>, ws: &Rc<WorkspaceNode>) {
+        self.surface.set_output(&ws.output.get());
+    }
+
     fn tl_change_extents(self: Rc<Self>, rect: &Rect) {
         // log::info!("xwin {} change_extents {:?}", self.data.window_id, rect);
         let old = self.data.info.extents.replace(*rect);