BATCH file that starts the ssh-agent

I have written a batch file that starts the ssh-agent and authenticates keys on the system with the ssh-agent in the MS-DOS prompt.  I have put the script in the `cmd` folder as that is the one that is added to the native prompt.  If the script is double-clicked on in explorer it starts a new prompt else if invoked from a current prompt it will just authenticate the keys.

It looks up the ssh-agent in the tasklist to make sure that multiple agents are not started.

It's not perfect, but I wondered if it would be useful to the project.  Happy to change it in any way you would like if you would find it a useful addition.