[Snek] mu, network REPL, echoing

[Misha Gusarov]

Hi.

I'm back to working on EV3 port of Snek, trying to get Mu REPL working.

telnet'ing to snekserver works well — telnet (or is it kernel?) handles
local echo and line editing.

Should Mu work in the same manner? I suppose it should, but I haven't found
any echoing in other REPLs in its source code, so I'm confused why they
don't need it, and how it works in other modes.

Best,
Misha.