mk-mod utility creates GOPROXY-compatible version of the module in the
current directory:
    mk-mod VCS-URL VCS-PATH MODULE-NAME VERSION
Only Git VCS is supported. Git tag's name must be equal to VERSION.
mk-mods iterates through all tags:
    mk-mods VCS-URL VCS-PATH MODULE-BASE-NAME

mk-list utility collects all known versions in current GOPROXY directory
and creates corresponding "list" files.

mk-goget creates go-import-compatible static files:
    mk-goget VCS-WEB-URL MODULE-NAME

For example:
    mkdir proxy
    cd proxy
    mk-mods https://git.cypherpunks.ru/balloon.git ~w/balloon go.cypherpunks.ru/balloon
    mk-mods https://git.cypherpunks.ru/gotai64n.git ~w/gotai64n go.cypherpunks.ru/balloon/tai64n
    mk-list
    cd ..

    mkdir goget
    cd goget
    mk-goget "http://www.git.cypherpunks.ru/?p=balloon.git" go.cypherpunks.ru/balloon
    mk-goget "http://www.git.cypherpunks.ru/?p=balloon.git" go.cypherpunks.ru/balloon/v2