Improve address label rendering.

Render addr:unit and addr:housename even if addr:housenumber is missing.

Render only addr:unit, when render = "unit-only" has been set in SQL,
i.e. render only addr:unit on entrances which have the same
addr:housenumber as the building they overlap with.

addressing.mss

@@ -12,8 +12,18 @@
 
 #addresses {
   [zoom >= 17] {
+    text-name: "";
+    text-placement: interior;
+    text-face-name: @book-fonts;
+    text-fill: @address-color;
+    text-halo-radius: @standard-halo-radius;
+    text-halo-fill: @standard-halo-fill;
+    text-size: 10;
+    text-wrap-width: 30; // 3.0 em
+    text-line-spacing: -1.5; // -0.15 em
+    text-margin: 3; // 0.3 em
     text-name: "[addr_housename]";
-    ["addr_housenumber" != null] {
+    ["addr_housenumber" != null]["render" = null] {
       text-name: [addr_housenumber];
       ["addr_housename" != null] {
         text-name: [addr_housenumber] + "\n" + [addr_housename];
@@ -25,16 +35,13 @@
         }
       }
     }
-    text-placement: interior;
-    text-face-name: @book-fonts;
-    text-fill: @address-color;
-    text-halo-radius: @standard-halo-radius;
-    text-halo-fill: @standard-halo-fill;
-    text-size: 10;
-    text-wrap-width: 30; // 3.0 em
-    text-line-spacing: -1.5; // -0.15 em
-    text-margin: 3; // 0.3 em
-    [zoom >= 18]["addr_unit" != null]["addr_housenumber" = null] {
+    ["addr_unit" != null]["addr_housenumber" = null]["render" = null] {
+      text-name: [addr_unit];
+      ["addr_housename" != null] {
+        text-name: [addr_unit] + "\n" + [addr_housename];
+      }
+    }
+    ["render" = "unit-only"] {
       text-name: [addr_unit];
     }
     [zoom >= 20] {