ssh-agent.exe and ssh-add.exe code updated and fixed to work in Windows.
For convenience of users, ssh-agent.exe starts a cmd shell with the
"SSH_AUTH_SOCK" and "SSH_AGENT_PID" environment variables set.
ssh-add.exe can be run immediately from the cmd shell. 'ssh-add -L" and
"ssh-add id_rsa" and "ssh-add -d id_rsa" are 3 useful commands to list,
add and delete keys from ssh-agent cache.