[NEW PORT] textproc/cast2gif: Tool to render Asciinema cast files to GIFs

[Nuno Teixeira]

Hello to all,

A tool to render textproc/py-asciinema cast files to GIF.
This is a pre-release.
Please test it and use https://github.com/katharostech/cast2gif/issues if
necessary.
Bug 251064 <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=251064>

Thanks,

Nuno Teixeira