Console|ResourceSystem: Improved "listmaps" command

Now operates much like the other resource listing commands in that
one may now specify an optional id prefix to match when generating
the listing. For example, the command "listmaps E1" when executed
with Ultimate Doom loaded will output only those maps whose URI
path begins with "E1" (i.e., only the maps of episode one).

doomsday/client/include/resource/mapdef.h

@@ -39,6 +39,21 @@ class MapDef : public de::PathTree::Node, public de::Record
         : Node(args), Record()
     {}
 
+    /**
+     * Returns a textual description of the map definition.
+     *
+     * @return Human-friendly description the map definition.
+     */
+    de::String description(de::Uri::ComposeAsTextFlags uriCompositionFlags = de::Uri::DefaultComposeAsTextFlags) const {
+        de::String info = de::String("%1").arg(composeUri().compose(uriCompositionFlags | de::Uri::DecodePath),
+                                               ( uriCompositionFlags.testFlag(de::Uri::OmitScheme)? -14 : -22 ) );
+        if(_sourceFile)
+        {
+            info += de::String(" " _E(C) "\"%1\"" _E(.)).arg(de::NativePath(sourceFile()->composePath()).pretty());
+        }
+        return info;
+    }
+
     /**
      * Returns the URI this resource will be known by.
      */