RDP: new global parameter rdp_map_keycode
This MR adds a new global option
rdp_map_keycode to the remmina.pref file [remmina_pref] section.
It can be used by the RDP plugin to do a mapping between a hardware_keycode to another one.
Should help to fix issue #1788 (closed)
Note: Remmina already has a native system to map GDK keysyms, see issue #1716, based on a file called
remmina.keymap can only map keysyms, which are key already mapped after internationalizaion. The RDP plugin does not make use of keysyms: it uses hardware_keycodes, hence
remmina.keymap cannot be used under freerdp.