eselect-python vs GVM

eselect-python has no write-up on Specifiction yet; its figures are above.

GVM is a free tool for managing Go versions on Linux and macOS. It installs and removes versions by tag, including releases and the tip version; `gvm listall` shows available release tags and can include weekly builds. Install options allow a source or name to be selected, along with settings for protobufs, build tools, and whether binaries are preferred or required. The `gvm diff` command reports files added to or removed from GOROOT. GVM also manages GOPATH package sets, including sets kept local to a repository, and can link project directories into GOPATH. Package sets can use their own native code and dependencies through an overlay prefix and related environment variables. The project supports version pinning, lockfiles, automatic switching, shell integration, and CI/CD use. Installation requires Bison; platform instructions also list tools such as Git, Mercurial, Make, and GCC. Compiling Go 1.5 or later requires an existing Go installation for bootstrapping, with Go 1.4 offered as an example. The repository includes an MIT license.