twisted: import from old packages feed

twisted: import from old packages feed

- update to latest version (16.0.0)
- change to one package containing all plugins/subprojects
- add license info
- add myself as maintainer

This builds one main package, instead of multiple packages like the old
packages feed, to match upstream. (Debian and Fedora are moving to a
single-package model as well.) The obvious downside is a larger install
size, but one main package should be easier to maintain in the future.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>