core: i18n refactoring:

- _() is no more installed in __builtin__
    - instead, there is a new sat.core.i18n module
    - added D_() method for deferred translation
    - languageSwitch method allow to dynamically change translation language
    - import gettext is tested against ImportError, and dummy methods are used when not available (mainly useful for Libervia)

src/core/i18n.py

@@ -0,0 +1,42 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# SAT: a jabber client
+# Copyright (C) 2009, 2010, 2011, 2012, 2013  Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+try:
+
+    import gettext
+
+    _ = gettext.translation('sat', 'i18n', fallback=True).ugettext
+    _translators = {None: gettext.NullTranslations()}
+
+    def languageSwitch(lang=None):
+        if not lang in _translators:
+            _translators[lang] = gettext.translation('sat', languages=[lang], fallback=True)
+        _translators[lang].install(unicode=True)
+
+except ImportError:
+
+    print "WARNING: gettext support disabled"
+    _ = lambda msg: msg # Libervia doesn't support gettext
+    def languageSwitch(lang=None):
+        pass
+
+
+D_ = lambda msg: msg # used for deferred translations
+

src/core/sat_main.py

@@ -17,6 +17,7 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+from sat.core.i18n import _
 from twisted.application import service
 from twisted.internet import defer
 

src/core/xmpp.py

@@ -17,6 +17,7 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+from sat.core.i18n import _
 from twisted.internet import task, defer
 from twisted.words.protocols.jabber import jid, xmlstream
 from wokkel import client, disco, xmppim, generic, compat, delay, iwokkel