Add i18n_fastgenerate

So the time-consuming i18n_extract step can be skipped for situations that only the translated strings are modified while the source strings are still the same.

pavelib/i18n.py

@@ -33,6 +33,15 @@ def i18n_extract(options):
     sh(cmd)
 
 
+@task
+def i18n_fastgenerate():
+    """
+    Compile localizable strings from sources without re-extracting strings first.
+    """
+    cmd = "i18n_tool generate"
+    sh(cmd)
+
+
 @task
 @needs("pavelib.i18n.i18n_extract")
 def i18n_generate():