BAT_THEME allows you to set a theme.
I also want to set --wrap never permanently, but there's no respective env var.

Why not do like "less", where the LESS env var can take any of the command-line options?
I'd suggest to use the name BAT_OPTS for this, since in the mind of Windows users BAT means "batch files".

(Note: I've added this setting to your bat() function as per #263)