Make type -a print all executables in PATH

```
> type -a python
python is /opt/local/Library/Frameworks/Python.framework/Versions/2.7/bin/python
python is /opt/local/bin/python
python is /usr/bin/python
Tyilo:~ > type python
python is /opt/local/Library/Frameworks/Python.framework/Versions/2.7/bin/python
```

Fixed #261