feat: Reading from STDIN #1153

A commonly used pattern with vim is

echo 'foo' | nvim -

This doesn't work with vimr following commands: echo 'foo' |vimr --wait --nvim - or echo 'foo' |vimr --wait - open file named -

Please consider adding reading from stdin. It would be especially useful if vimr --wait-window file1 would exit when the window with file1 closed. My use case is Alfred integration, where I'd like to use VimR as a universal action.