Useful comment

lib/datastore.js

@@ -14,6 +14,8 @@ function Datastore (filename) {
   this.filename = filename;
   this.data = [];
 
+  // We keep internally the number of lines in the datafile
+  // This will be used when/if I implement autocompacting when the datafile grows too big
   this.datafileSize = 0;
 }