Bug with Base16 option

Bug with Base16 option

A user asked on GitHub clarification on using the --base16 option, not realizing that this option still requires the -s option to specify the theme name:

https://github.com/tajmone/highlight/issues/3

when I use the --base16 option - as indicated in the following line - to select the ashes base16 theme I get the following error:

highlight -O rtf --base16 ashes file.js | pbcopy

cannot open themes/base16/edit-kwrite.theme: No such file or directory

Please can you assist as to what is causing this issue ?

His question brought up two issues and a bug:

1. The help is not clear enough on the fact that this option doesn't dispense from using also -s.
2. The --base16 option could become a variant of -s (after all, they point to different folders).
3. It causes Highlight to look for the default theme in themes/base16, which is a bug.

For the bug, maybe Highlight should either ignore the base16 folder if no theme is specified, or else fallback on another default theme from among the base16 themes.