Create an installer for the plugin

[pre-martin]

As the plugin uses the folder images/custom for custom (user supplied) images (see #133) , we cannot rely any longer on the default mechanism of the Stream Deck software: The default mechanism is to delete the whole plugin folder, which would erase all user supplied content.

The installer must:

• Check for the .NET runtime and install it if required
• Stop the Stream Deck software
• Delete the plugin, but retain the folder with the custom images
• Unpack the new plugin
• Start the Stream Deck sofware

Preferably, the installer is an exe file that contains the plugin bundle.