Make method naming more consistent.

* Use id() for methods returning a string used to represent
    some type of object.
  * Use displayName() for strings that are meant to be user
    visible.
  * Quieten some warnings while touching the files anyway.
  * Move Factories to their products in the plugins where that
    was not done before.

Reviewed-by: dt

src/plugins/designer/settingspage.cpp

@@ -50,7 +50,7 @@ QString SettingsPage::id() const
     return m_designerPage->name();
 }
 
-QString SettingsPage::trName() const
+QString SettingsPage::displayName() const
 {
     return m_designerPage->name();
 }
@@ -60,7 +60,7 @@ QString SettingsPage::category() const
     return QLatin1String(Designer::Constants::SETTINGS_CATEGORY);
 }
 
-QString SettingsPage::trCategory() const
+QString SettingsPage::displayCategory() const
 {
     return QCoreApplication::translate("Designer", Designer::Constants::SETTINGS_TR_CATEGORY);
 }