X11 Keylogger

This module binds to an open X11 host to log keystrokes. This is a fairly
close copy of the old xspy c program which has been on Kali for a long time.
The module works by connecting to the X11 session, creating a background
window, binding a keyboard to it and creating a notification alert when a key
is pressed.

One of the major limitations of xspy, and thus this module, is that it polls
at a very fast rate, faster than a key being pressed is released (especially before
the repeat delay is hit). To combat printing multiple characters for a single key
press, repeat characters arent printed when typed in a very fast manor. This is also
an imperfect keylogger in that keystrokes arent stored and forwarded but status
displayed at poll time. Keys may be repeated or missing.