Support for non ASCII character set

[kishaningithub]

It would be great if the symbol set is expanded to include spanish characters

Example symbols - ÇÑñ¿ç

The important point is these symbols belong to UTF-16 character set
and because of this the len function has to be replaced with utf8.RuneCountInString as it deals with runes instead of bytes

[chr4]

This looks like a valid request! Thanks for the suggestion.

I'd suggest to create a different set for this though, as those characters are hard to type for people with different keyboard layouts, and I don't think it would be wise to include them by default in symbols.
Maybe, we can have something like language-based symbol strings, that can be enabled using a certian flag? (e.g. -l es in your case, but this could also cover other symbols, even arabic or chinese characters).

Pull requests welcome!