[python] fix sending lines to ipython

[lotabout]

In ipython >= 5, the autoindent feature is deprecated. Thus if we send multiple lines directly to it, the indentation will go wild. Notice that with ipyton >= 5, multiple line paste(via Ctrl-V or Command-V) is well supported. This this commit try to utilize the -p option of tmux paste-buffer which will use bracket paste mode.

Checkout here for more information: https://cirw.in/blog/bracketed-paste