Peer: Rework and improve *defaultName

[muellmusik]

The single commit in this PR does the following:

• whoami is deprecated, and has been replaced with id for osx and windows
• use "echo %username%" on Windows as availability of whom is limited on windows
• fall back on hostname if for some reason it doesn't work

This will hopefully solve a problem where whomami seemed to return an empty string for some reason.

NB I don't have a reproducer for the problem, but it seems to be gone, and I haven't been able to test the new version on Windows (@bagong maybe you could help?), though I've confirmed the cl command works. Signed-off-by: Scott Wilson i@scottwilson.ca

[bagong]

I will be working on SC Windows stuff from the 16th onward and try it out.