Release v5 of the kernel to opam?

[jaredly]

Last year you said you wanted to upgrade the server as well, but wouldn't it work fine to just have the server still use the old protocol (and the old version of the iocaml kernel)? It's only people using jupyter directly that need the new protocol anywayss

[andrewray]

I guess that's OK. I do need to get the 0.4.x series back into shape again first though.