Support window-rules

Two types of window rules are supported, actions and properties. They are
defined as shown below.

    <windowRules>

      <!-- Action -->
      <windowRule identifier="some-application">
        <action name="Maximize"/>
      </windowRule>

      <!-- Property -->
      <windowRule identifier="foo*" serverDecoration="yes|no"/>

    </windowRules>

Rules are applied if windows match the criteria defined by the
'identifier' attribute which relates to app_id for native Wayland windows
and WM_CLASS for XWayland clients.

Matching against patterns with '*' (wildcard) and '?' (joker) is
supported.

Add 'serverDecoration' property.

docs/labwc-config.5.scd

@@ -330,6 +330,48 @@ The rest of this man page describes configuration options.
 	any motion events while a keyboard is typing, and for a short while
 	after as well.
 
+## WINDOW RULES
+
+Two types of window rules are supported, actions and properties. They are
+defined as shown below.
+
+```
+<windowRules>
+
+  <!-- Action -->
+  <windowRule identifier="">
+    <action name=""/>
+  </windowRule>
+
+  <!-- Property -->
+  <windowRule identifier="" serverDecoration="" />
+
+</windowRules>
+```
+
+*Actions*
+
+*<windowRules><windowRule identifier="">*
+	Define a window rule for any window which matches the criteria defined
+	by the attribute *identifier*. Matching against patterns with '\*'
+	(wildcard) and '?' (joker) is supported. Pattern matching is
+	case-insensitive.
+
+	*identifier* relates to app_id for native Wayland windows and WM_CLASS
+	for XWayland clients.
+
+*Properties*
+
+Property values can be *yes*, *no* or *default*.
+
+If a window matches criteria for multiple rules which set the same property,
+later config entries have higher priority. *default* can be useful in this
+situation.
+
+*<windowRules><windowRule serverDecoration="">* [yes|no|default]
+	*serverDecoration* over-rules any other setting for server-side window
+	decoration on first map.
+
 ## ENVIRONMENT VARIABLES
 
 *XCURSOR_THEME* and *XCURSOR_SIZE* are supported to set cursor theme

docs/rc.xml.all

@@ -374,4 +374,13 @@
     </device>
   </libinput>
 
+  <!--
+  <windowRules>
+    <windowRule identifier="*">
+      <action name="Maximize" />
+    </windowRule>
+    <windowRule identifier="some-application" serverDecoration="yes" />
+  </windowRules>
+  -->
+
 </labwc_config>