Fixed crash related to missing MSVC++ 2010 Redist

The program will no longer crash if Microsoft Visual C++ 2010
Redistributable is not installed.
The .NET installer is now removed at uninstall

Fixed uninstallation to also remove the .NET installer. The old
uninstall.exe would leave both the installer and the folder untouched.
Show a message when the overlay has been added

A text saying "Overlay added!" will be shown for 3 seconds after the
overlay has been added. This is to indicate that the overlay actually
was added.