Remove a bunch of deadc0de
Get the PC Joystick working with glvideo renderer
Fixes keypad joystick emulation with glvideo

    * This prevents resetting the joystick to the origin too soon when key is being held down
    * Verified doesn't affect legacy X11 xvideo input processing
Fix key input handling in GLUT/glvideo

    * TIL GLUT constants for certain special keys map to ascii (for example GLUT_KEY_ALT_L == 116/'t') ... of course
      this was playing hell with the emulator's key input handling
    * Now we directly convert regular keys rather than pushing them down the special path
    * Also separateds CAPS_LOCK hack into its own inline function
Remove deadc0de key handling paths (leftover from X11)
Refactor : separate glut input handling into its own file
Bugfix : properly handle control-modified keys

    * GLUT sends the raw ascii ctrl-values, so we merely send them along in a "cooked" mode
        + It may be that some strange ctrl combinations (saw CTRL-~ or CTRL-ESC) are not properly handled this way, but
        ... not sure what can be done about this (doesn't seem to be a way to force glut to send us the non-cooked keys)
    * Legacy X11 input continues to be sent as raw values (which arguably is a better way)