Shaarli's translation

* translation system and unit tests
 * Translations everywhere

Dont use translation merge

It is not available with PHP builtin gettext, so it would have lead to inconsistency.

plugins/demo_plugin/demo_plugin.php

@@ -433,3 +433,12 @@ function hook_demo_plugin_render_feed($data)
     }
     return $data;
 }
+
+/**
+ * This function is never called, but contains translation calls for GNU gettext extraction.
+ */
+function demo_dummy_translation()
+{
+    // meta
+    t('A demo plugin covering all use cases for template designers and plugin developers.');
+}