Use QCommandLineParser to handle the command line arguments

This gives us a nice --help and --version option for free.
Support recent files in jump list on Windows

Use QtWinExtras add-on to support the recent files category in the task
bar jump list on Windows.
Replace options button in FindReplaceWidget with QAction in QLineEdit

Use the new Qt 5.2 functionality to add QAction to QLineEdit for
showing the find options menu.

Remove the previous used toolbutton.
Add Qt5WinExtras.dll to WiX installer file
COVERITY-14276/14277: unchecked dynamic_cast

Fix possible null pointer dereferences caused by unchecked dynamic_cast
calls in DiscountMarkdownConverter class.
Merge branch 'feature/upgrade-qt5.2' into develop

Conflicts:
	app/mainwindow.cpp