Unduplicated the code that initializes editor settings

This stuff was all over the place, a relic from before the editor
settings were unified. Now the initialization is only done in
TextEditorSettings.

Fixes the .pro file editor and the generic project files editor, which
before only used the font settings.

src/plugins/texteditor/texteditorsettings.h

@@ -36,6 +36,7 @@
 
 namespace TextEditor {
 
+class BaseTextEditor;
 class BehaviorSettingsPage;
 class DisplaySettingsPage;
 class FontSettingsPage;
@@ -59,6 +60,8 @@ public:
 
     static TextEditorSettings *instance();
 
+    void initializeEditor(BaseTextEditor *editor);
+
     FontSettings fontSettings() const;
     TabSettings tabSettings() const;
     StorageSettings storageSettings() const;