Clean headers in Utils.

Forward-declare QGraphicsOpacityEffect in DetailsButton,
QProcessEnvironment in Environment, QFileInfo in fileutils,
QUrl in IWelcomePage, FancyLineEdit in PathChooser and
remove unneeded headers.

Change-Id: I7d5f273530dd2059bbdaf0899f0a3bc7e49e8482
Reviewed-by: hjk <hjk121@nokiamail.com>

src/libs/utils/pathchooser.cpp

@@ -29,6 +29,7 @@
 
 #include "pathchooser.h"
 
+#include "fancylineedit.h"
 #include "basevalidatinglineedit.h"
 #include "environment.h"
 #include "qtcassert.h"
@@ -38,15 +39,9 @@
 
 #include <QDebug>
 #include <QDesktopServices>
-#include <QDir>
-#include <QEvent>
 #include <QFileDialog>
-#include <QFileInfo>
 #include <QHBoxLayout>
-#include <QLineEdit>
-#include <QProcess>
 #include <QPushButton>
-#include <QSettings>
 
 /*!
     \class Utils::PathChooser