tmux-send-text allows sending an argument, when supplied the argument
will be sent to the REPL instead of the current selection.
tmux-send-text also keeps kak focussed, which does not happen in the x11
variant as it uses xdotool to switch window.
this patch allows:
* Passing an argument to x11-send-text, so that value will be sent
instead of the current selection.
* We capture the window id of the current (presumably kak window)
before we use xdotool to switch window. We can therefore switch back to
kak afterwards (which we do)
Now it uses the window id to identify the REPL window. It is stored in
the option x11_repl_id. That way it is possible to have different REPLs
for different buffers or windows.
It's unclear what the `send-text` alias does at first glance,
so prefixing it with "repl-" both fixes that and helps make it
discoverable via the command prompt's fuzzy matcher.
The `repl` alias also seems too generic a name, the "-new" suffix
should hopefully give a hint that it creates a new window.
