This commit changes the way ports are aggregated in the Docker provider. Previously ports were aggregated by their "number", but that is not a truly unique representation. Instead, the protocol is now taken into account when generating the port map. Fixes GH-5527
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.