libxbps: improve code to match replaced package patterns.

The replaces code now checks all package dictionaries in the
transaction dictionary, and the sorting algorithm will put packages
to be removed at the head of the tailq.

This should fix issue 11 in googlecode.

include/xbps_api_impl.h

@@ -172,10 +172,9 @@ int HIDDEN xbps_file_chdir_exec(const char *, const char *, ...);
 
 /**
  * @private
- * From lib/package_replaces.c
+ * From lib/transaction_package_replace.c
  */
-int HIDDEN xbps_repository_pkg_replaces(prop_dictionary_t,
-					prop_dictionary_t);
+int HIDDEN xbps_transaction_package_replace(prop_dictionary_t);
 
 /**
  * @private