Change I/O signals to pass a unique window ID

Change the 'char-input', 'line-input', and 'text-buffer-output'
signals to pass a unique window ID string as well as the
window rock value. If a client program wants to keep track of
input and output in all windows, then the window rock will
not do by itself - all open windows might have rock 0, for
example. The string ID is guaranteed to be unique for each
window, though its contents are implementation-defined.
Keep track of input and output in multiple windows in the player

In the ChimaraIF player widget, keep track of input and
output in all text buffer windows, not just one.