chore(languages): add integration with transifex

.tx/config

+[main]
+host = https://www.transifex.com
+
+[linphone-desktop.ts]
+file_filter = assets/languages/<lang>.ts
+source_file = assets/languages/en.ts
+source_lang = en
+type = QT

CMakeLists.txt

@@ -260,7 +260,7 @@ set(QRC_RESOURCES resources.qrc)
 
 set(LANGUAGES_DIRECTORY "${ASSETS_DIR}/languages")
 set(I18N_FILENAME i18n.qrc)
-set(LANGUAGES en fr)
+set(LANGUAGES en fr_FR)
 
 # ------------------------------------------------------------------------------
 

assets/languages/CMakeLists.txt

@@ -6,7 +6,7 @@
 # See: https://bugreports.qt.io/browse/QTBUG-31860
 #
 # On October 17, 2016, this issue was marked `invalid` but it's a
-# bullshit. It's not tolerated to remove sources files.
+# bullshit. It's not tolerated to remove source files.
 set_directory_properties(PROPERTIES CLEAN_NO_CUSTOM true)
 
 # Build languages resource file.