Do not ignore `BAT_CONFIG_PATH` if it doesn't exist. Both when
generating a new config file with `--generate-config-file` and
when attempting to read the config.
Also, provide a better error message in case the file can not
be created.
closes#1550
closes#1510
The change in `create_highlighted_versions.py` fixes a "unknown theme
"'1337'" warning. The single quotes were wrong. `bat` was always falling
back to the default theme, so let's use that for now.
David Peter