New "ctype" option in uscan

[Xavier <yadd@debian.org>]

Hi,

I added a new feature in uscan to help uscan comparison when components
are embedded, especially when "checksum" target is used: if "ctype"
exists, uscan will use "version" value from package.json (JavaScript) or
META.json (Perl) to get current component value.

For now, only "nodejs" and "perl" values are accepted.

This feature comes with devscripts 2.20.5.

Cheers,
Xavier