Menu key support and key configuration

[je-vv]

Several VNC clients, like tiegerVNC support launching a client menu, with all sorts of options (not all available at least yet for wlvncc), but disconnecting is one of the main drop down menu. By default F8 is used to launch such menu, but it also can be configured through the argument -MenuKey which is pretty useful since F keys have several users. Actually I call vncviewer with -MenuKey F12 since F12 is not commonly used, neither one usually create that many workspaces (F is usually associated to the corresponding workspace number).

So, supporting menu launching through a key, and being able to change the default key chosen to launch it, is really handy, particularly if one is calling for wlvncc not from the command line, but from a *.desktop file instead, so that it can be found through freedesktop applications menus such as wofi (then there's no need to go look for the process ID on a terminal, just to disconnect from the remote session).

This is very important when not calling the VNC client from the CLI, which is the way I call the tigervnc client which I currently use. That and having a GUI password prompt (or the not so secure passwd option to use ~/.vnc/passwd obfuscated password file), are really key when not calling the VNC client from the CLI.

Many thanks !