GenericProject: Modernize

* Use pragma once
* Use overrides
* Clean up here and there (mostly in the headers)

Change-Id: Ib33b6a6aa1a285d281f3d8b940fe654af3941554
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/genericprojectmanager/filesselectionwizardpage.cpp

@@ -34,8 +34,6 @@
 #include <utils/wizard.h>
 
 #include <QVBoxLayout>
-#include <QLineEdit>
-#include <QPushButton>
 
 namespace GenericProjectManager {
 namespace Internal {