Clean headers in ProjectExplorer.

Change-Id: If61a8a91d2a39c5c97974a5bfcef91892b68d3f1
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/projectexplorer/removetaskhandler.cpp

@@ -33,12 +33,7 @@
 #include "task.h"
 #include "taskhub.h"
 
-#include <coreplugin/coreconstants.h>
-
-#include <QDir>
 #include <QAction>
-#include <QApplication>
-#include <QClipboard>
 
 using namespace ProjectExplorer::Internal;