Fixes "too many opened files" error (#120)

* Fixes a problem with too many opened files when treating a large number of input files.

* Tab to space.

lib/index.js

@@ -91,6 +91,7 @@ function plugin(opts){
   return function(files, metalsmith, done){
     var metadata = metalsmith.metadata();
     var matches = {};
+    var templates = {};
 
     /**
      * Process any partials and pass them to consolidate as a partials object
@@ -114,7 +115,13 @@ function plugin(opts){
       debug('stringifying file: %s', file);
       var data = files[file];
       data.contents = data.contents.toString();
-      matches[file] = data;
+      var template = metalsmith.path(dir, data.layout || def);
+      if (!templates[template]) {
+        debug('found new template: %s', template);
+        templates[template] = file;
+      } else {
+        matches[file] = data;
+      }
     });
 
     /**
@@ -153,8 +160,17 @@ function plugin(opts){
     }
 
     /**
-     * Render all matched files
+     * Render all matched files.
      */
-    each(Object.keys(matches), convert, done);
+    function renderFiles(err) {
+      if (err) {
+        return done(err);
+      }
+      each(Object.keys(matches), convert, done);
+    }
+
+    // Do a first pass to load templates into the consolidate cache.
+    each(templates, convert, renderFiles);
+
   };
 }