[keyboard] Re-jig translation extraction

- Use classes to prompt lupdate to extract with a better
  context (e.g. the class name, rather than plain "QObject")
  so that the translation-lookup can use the named context.
- Add hard-coded "default" variant
- Add totally bogus Tajik translations, for testing purposes

src/modules/keyboard/Config.cpp

@@ -564,4 +564,5 @@ Config::setConfigurationMap( const QVariantMap& configurationMap )
 void
 Config::retranslate()
 {
+    retranslateKeyboardModels();
 }

src/modules/keyboard/KeyboardLayoutModel.cpp

@@ -20,6 +20,18 @@
 
 static QTranslator* s_kbtranslator = nullptr;
 
+void
+retranslateKeyboardModels()
+{
+    cqDeleter< QTranslator > d{ s_kbtranslator };
+    if ( !s_kbtranslator )
+    {
+        s_kbtranslator = new QTranslator;
+    }
+    d.preserve = CalamaresUtils::loadTranslator( QLocale(), QStringLiteral("kb_"), s_kbtranslator );
+}
+
+
 XKBListModel::XKBListModel( QObject* parent )
     : QAbstractListModel( parent )
 {

src/modules/keyboard/KeyboardLayoutModel.h

@@ -146,4 +146,8 @@ public:
     void setVariants( QMap< QString, QString > variants );
 };
 
+/** @brief Adjust to changes in application language.
+ */
+void retranslateKeyboardModels();
+
 #endif  // KEYBOARDLAYOUTMODEL_H

src/modules/keyboard/layout-extractor.py

@@ -58,10 +58,11 @@ def scrape_file(file, modelsset, layoutsset, variantsset):
 def write_set(file, label, set):
     file.write("/* This returns a reference to local, which is a terrible idea.\n * Good thing it's not meant to be compiled.\n */\n")
     # Note {{ is an escaped { for Python string formatting
-    file.write("static const QStringList& {!s}_table()\n{{\n\treturn QStringList {{\n".format(label))
+    file.write("class {!s} : public QObject {{\nQ_OBJECT\npublic:\n".format(label))
+    file.write("\tconst QStringList& table()\n\t{\n\treturn QStringList {\n")
     for x in sorted(set):
-        file.write("""\t\tQObject::tr("{!s}", "{!s}"),\n""".format(x, label))
-    file.write("\t\tQString()\n\t};\n}\n\n")
+        file.write("""\t\ttr("{!s}", "{!s}"),\n""".format(x, label))
+    file.write("\t\tQString()\n\t};\n}\n}\n\n")
 
 cpp_header_comment = """/*   GENERATED FILE DO NOT EDIT
 *
@@ -84,6 +85,7 @@ if __name__ == "__main__":
     models=set()
     layouts=set()
     variants=set()
+    variants.add( "Default" )
     with open("/usr/local/share/X11/xkb/rules/base.lst", "r") as f:
         scrape_file(f, models, layouts, variants)
     with open("KeyboardData_p.cxxtr", "w") as f: