Reducing class duplication with Qt

Some of the splitting for kdelibs are easily blocked by classes mentionned here. The goal of this epic, is to determine for each class what it will become. Possible solutions are:

go straight in hel^Wkde4support if it is obsoleted completely by a class in Qt;
have its features ported to the corresponding class in Qt 5, then moved to kde4support (in which case a corresponding task has to be opened in one of the Qt 5 epics;
if it provides a valid feature on its own on top of Qt (real novelty, not just some addon cramed into a subclass), decide on which framework it goes to;
if it's purely about integration among KDE applications, go straight to the upcoming kde "consistency" framework (Tier 4).

A row is marked as "done" when the investigation is done and TODOs have been added to the Qt-5.1 or kdelibs_cleanups pages. Not when the job itself is done.

Status	Description	Comment
DONE	KApplication : public QApplication	kde4support is the plan, but we should check for specifics
DONE	KComboBox : public QComboBox, public KCompletionBase	major features on top of Qt (completion), plus lots of small API things that should go into QComboBox (contains, ...). Final destination: a framework with the completion stuff?
DONE	KLineEdit : public QLineEdit, public KCompletionBase	major features on top of Qt (completion), plus lots of small API or behaviors that should go into QLineEdit (see Qt 5.1 merging). Final destination: a framework with the completion stuff?
DONE	KRestrictedLine : public KLineEdit	Move to kde4support. Very few users, and a validator can be used instead.
DONE	KDialog : public QDialog	Mostly convenience and consistency -> tier4, after porting the rest of kdelibs away from it (except tier4 and kde4support/kde3support)
DONE	KDialogButtonBox : public QDialogButtonBox	Deprecate, move to kde4support, using QDialogButtonBox directly takes 2 or 3 lines of code (when using KGuiItem).
DONE	KDoubleValidator : public QDoubleValidator	Deprecate, move to kde4support, the merging of the locale stuff makes it obsolete.
DONE	KIcon : public QIcon	Discussed on kde-frameworks-devel, replace with one method.
DONE	KLibrary : public QLibrary	Adds KF5 search paths, so moved to the kservice framework. Should become mostly internal, though...
DONE	KPluginLoader : public QPluginLoader	Adds KF5 search paths, so moved to the kservice framework.
DONE	KListWidget : public QListWidget	only adds auto-select support, which was mainly meant for filemanagers. Port kdelibs to QListWidget, then move KListWidget to kde4support.
DONE	KMainWindow : public QMainWindow	Goes to kconfig-widgets except for the "setCaption" part which should be covered by the platform integration plugin in Qt
DONE	KMenu : public QMenu	Title item support, and keyboard navigation. Could be added to QMenu.
DONE	KMenuBar : public QMenuBar	This one goes straight to kde4support, it's only feature probably doesn't even work anymore on modern systems (top level menubar), and it's getting replaced through dbusmenu
DONE	KProcess : public QProcess	Code should be ported to QProcess (except kpty).
DONE	KPushButton : public QPushButton	DnD support, only used in KUrlRequester in kdelibs -> create a helper class based on event filtering. Auth support -> rename to KAuthPushButton. Delayed menu support -> add to Qt 5.1..
DONE	KSplashScreen : public QSplashScreen	Only exists for KDE Xinerama settings, which are gone. -> kde4support
DONE	KStatusBar : public QStatusBar	KStatusBar adds convenience to QStatusBar by making items changeable by id (but the same could easily be done by keeping a pointer to the QLabel widgets passed in) and emitting a signal when items are clicked (Again keeping pointers to the QWidgets would give the same signals)
DONE	KSystemTrayIcon : public QSystemTrayIcon	KSystemTrayIcon is to be deprecated in favor of KStatusNotifierItem. Moved by aseigo already, he also took care of adding the important bit to KStatusNotifierLegacyIcon which now inherits from QSystemTrayIcon directly.
DONE	KTabBar: public QTabBar	TODO added to cleanup page
DONE	KTabWidget : public QTabWidget	TODO added to qt5.1 epic
DONE	KTextBrowser : public QTextBrowser	Adds icons in popup menu, support for clicking on mailto and http urls, user-configurable wheel event (zoom or scroll), then kde4support
DONE	KTextEdit : public QTextEdit	Background spellchecking in QTextEdit, then tier4/consistency
DONE	KToolBar : public QToolBar	Goes to kconfig-widgets except for the "loadKDESettings" part which should be covered by the platform integration plugin in Qt
DONE	KUndoStack : public QUndoStack	Could become two methods in a namespace, no subclass needed.
DONE	KUrl : public QUrl	Finish porting to QUrl, then move to kde4support
DONE	KAction : public QWidgetAction	See spreadsheet by Valentin Rusu, on k-f-d
DONE	KDateTime	Already part of jlayt's plans, I think
DONE	KLocale	Already part of jlayt's plans
DONE	KColorDialog	KColorDialog is almost identical to QColorDialog with slightly different api. KColorDialog adds a web color lineedit and a dropper button. Probably should go to kde4support
DONE	KMessageBox	Goes to tier4/consistency
DONE	KInputDialog	Some extra features in Qt, then goes to kde4support
DONE	KFileDialog	QUrl variants in QFileDialog then kde4support
DONE	KProgressDialog	Goes to kde4support