wip: saner rendering on arranger header

layout/src/map.rs

@@ -10,6 +10,16 @@ pub fn map_south<O: Output>(
             Fill::x(item))))
 }
 
+pub fn map_east<O: Output>(
+    item_offset: O::Unit,
+    item_width:  O::Unit,
+    item: impl Content<O>
+) -> impl Content<O> {
+    Push::x(item_offset,
+        Align::w(Fixed::y(item_width,
+            Fill::y(item))))
+}
+
 pub struct Map<'a, A, B, I, F, G>(pub PhantomData<&'a()>, pub F, pub G) where
     I: Iterator<Item = A> + Send + Sync,
     F: Fn() -> I + Send + Sync + 'a,