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/fixed.rs

@@ -4,7 +4,7 @@ use std::{
     ops::{Add, AddAssign, Sub, SubAssign},
 };
 
-#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
 #[repr(transparent)]
 pub struct Fixed(pub i32);
 
@@ -37,6 +37,10 @@ impl Fixed {
         self.0 >> 8
     }
 
+    pub fn round_up(self) -> i32 {
+        (self.0 + 255) >> 8
+    }
+
     pub fn apply_fract(self, i: i32) -> Self {
         Self((i << 8) | (self.0 & 255))
     }