Rewrite startup script in C++

[keithw]

[rpwoodbu]

As it turns out, I've done a fair amount of this work as part of Mosh for Chrome. I just refactored it so that the SSH login stuff is all contained in ssh_login.{cc,h}. It uses libssh, which may be good or bad from your perspective. More refactoring would have to be done to tease it apart from NaCl, but if this is something you'd find useful, I'll see what I can do. It would definitely be preferable to have a single implementation that could link into a standalone startup program as well as my NaCl binary.

[rpwoodbu]

Hey wait, is there any different between this issue and issue #96? Looks like much of this work is already done.

[zenware]

I'm just reading through all the issues and pull requests on this project because I have nothing better to do right now, and it looks like this should probably be closed because #96 is almost definitely a duplicate with a lot more progress.