#95 Better clipboard support

The clipboard works really good using xclipboard, xclip(1) (only the -o command, -i doesn't work at all), pbpaste(1) and pbcopy(1) on MacOS, and sometimes Cmd+v on MacOS.

I would like to support xclip fully and support Mac's cmd+v fully. Right now, the cmd+v only works on iTerm2, which I don't use.

cmd-v works in kitty term as well but only if the data is ACSII. If there are any unicode chars it won't paste anything.