Renamed ssh into ssh-ident.
Large single commit:
- create missing directories automatically
- don't require profiles by default
- by default, load keys from ~/.ssh/
This means that the script can be used just to load ssh-agent and key.

Additionally:
- updated docstrings as required.
- patterns are now regular expressions.
- all errors are printed to >>sys.stderr
- don't print an error if no config was found (normal)