Add more possible file extensions for the Perl 6 lexer
Add more possible file extensions for the Perl 6 lexer

According to S01, any Perl file extension with a '6' in it (ex. .pm6) can
be interpreted as a Perl 6 file extension.

zmughal/pygments-mirror,sol/pygments,zmughal/pygments-mirror,sol/pygments,sol/pygments,sol/pygments,sol/pygments,zmughal/pygments-mirror,sol/pygments,zmughal/pygments-mirror,zmughal/pygments-mirror,sol/pygments,sol/pygments,zmughal/pygments-mirror,zmughal/pygments-mirror,sol/pygments,sol/pygments,sol/pygments,zmughal/pygments-mirror,sol/pygments,sol/pygments,zmughal/pygments-mirror,zmughal/pygments-mirror,zmughal/pygments-mirror,zmughal/pygments-mirror,zmughal/pygments-mirror,sol/pygments,zmughal/pygments-mirror,zmughal/pygments-mirror,zmughal/pygments-mirror,zmughal/pygments-mirror,zmughal/pygments-mirror,zmughal/pygments-mirror