Add option to run even if sixel is not not 'supported'

[yiannikos-p]

I am running a fork of alacritty that supports sixel (https://github.com/microo8/alacritty-sixel) but since it is not on the list of supported terminals i guess I cannot run the software. Instead of updating the list with all terminals there should be an option to 'force' running or change a config file so that it doesn't do the check.

[hackerb9]

vv doesn't check a list of terminals. It simply asks the terminal if it supports sixel. The Alacritty fork should have added the sixel capability ("4") to the Device Attributes. Would you be willing to post your bug report on the Alacritty fork?

By the way, here is the code vv uses; you can see it is pretty simple:

    # IS TERMINAL SIXEL CAPABLE?		# Send Device Attributes
    if read -a REPLY -s -t 1 -d "c" -p $'\e[c' >&2; then
       for code in "${REPLY[@]}"; do
	   if [[ $code == "4" ]]; then
	       hassixel=yup
	       break
	   fi
       done
    fi